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View Full Version : Went back to stock, sort of....


ausie
05-29-2006, 12:53 PM
I was contemplating doing this for some time and getting pulled over a while back influenced me even further. The reason why I did not was that I like the cat-back that is on the car; SLP Loudmouth. Since I had two options sitting on the basement floor I decided to install the better of the two (2004 and 2001 exhaust). The 01 exhaust had some mild tones to it when it was on the 01 and since it was lacking the goofy center pipe with some sort of steel wool packing in it I decided to go for the 01 exhaust. One reason why I went back to a stock exhaust is that there seemed to be a lack of boost almost like a turbo lag. The good thing about that was I could drive almost anywhere without pulling in any boost and as a benefit I was getting great gas milage. The 01 factory exhaust is almost as quiet as the 04 exhaust but I can at least hear it to some degree. Of course I do like the rich tones I got from the SLP as well as the rumble when coasting down a hill when in gear, I just wanted a change for a little while. Considering how long I had the SLP on the car, it still looks like it did when it came out of the box with the exception of road grime on it. I plan to clean it up and reinstall it, but have it welded together rather than clamped. There is one thing I did not expect with the factory 01 exhaust was feeling that the car made more power :scratch: . Perhaps a little back pressure can be a good thing since now the boost guage has become reanimated on the slightest throttle changes. One thing is certain I can hear every time the tires break loose where the aftermarket exhaust would mask it from being heard. On the lighter side of that, the Firestone tires do make some noise but it still remains tolerable.

InfamousSVT
06-01-2006, 11:15 PM
Backpressure will give you that extra boost you may or may not have lost when installing after market exhaust. If you like the SLP sound, but want it a little bit quiet while cruising you can always get an Off-road mid-pipe and then go with a turbo type muffler.
Then while cruising around it will be mild until you hit the happy pedal and then it'll wake it up for sure :D

ausie
06-02-2006, 07:44 AM
I have thought about that as well as the FR500 exhaust. I will be putting the SLP back on eventually. So far I believe the car is much quicker now but that may be because I cannot hear the exhaust as much and I am more into the throttle than I was with the louder exhaust. Since I had the old exhaust from the 01 Cobra which has different mufflers on it (at least the stamped number is different than the 04 cans) why not use it? Too bad I do not have any dyno numbers to compare (aftermarket cat back to stock cat back). I was thinking on hitting the drag stip a few times with the factory exhaust in place and compare that to the spread sheet I created with all the time slips from last year (I included weather conditions along with mods or changes to the car along with all the times and speeds from the time slips). Not a great comparison since the conditions change from each racing sesssion. From a driver's viewpoint I do feel a difference and I do not have to be a passenger in my own car to notice how quick it really is. Perhaps it is the volume of audiable noise you hear that makes you think it should be going faster and also may cause you to be more conservative on the throttle.

Right now, I like what I feel and do not mind the softer exhaust note and since the cat-back was just sitting there taking up space on the basement floor it served its purpose for now. Gas milage has not changed much since I swapped the pipes but that is too soon to tell if it will get worse since I am more on the throttle and into boost than I was whith the SLP in place. Having a loud exhaust does have its benefits; awsome rumble = something worth listening too, lack of large animals standing in the middle of the street (deer, and what ever walks the earth in my area), but they also have thier disadvantage like a police officer that claims you are drag racing on the street when you slowly accelerate to the speed limit. I do not mind getting pulled over if the reason for it is legitimate, but having the reason being just an assumption because the car makes noise is something that is not appreciated.

ausie
06-03-2006, 09:22 AM
Could not make it to the track due to rain. That will give me more time to aquire an IRS cover brace before I break something.

ausie
06-03-2006, 01:40 PM
Had a few tools sitting around the house, like a vacuum/pressure guage and a shop vac with extra plumbing. I decided to take one of the extentions from the shop vac (can be used as a leaf blower as well) and drilled a 1/4 inch hole into it. Connected the vacuum/pressure guage to it to get a reading of how much back pressure is created when attached to the exhausts. I will assume that the 01 factory cat back is simlar to that of the 04 for the time being. I tested out the rig without any load and sure enough no reading on the guage. I then blocked off the output of the blower to get a maximum reading of 2 psi of pressure. When connected to the SLP Loudmouth the reading was neutral or 0 psi. However when connected to the 04 factory cat back, the pressure reading was close to 1psi. Not sure if I want to take off the 01 exhaust at this point to get a reading but I would assume it would have the same reading as the 04 exhaust. I still have plans on reinstalling the SLP cat-back but will want to get some track time in on the 01 exhaust and see if there is a slump in performance or not.

ausie
06-07-2006, 08:12 AM
The silence will not last for too long since I am already missing the good old tones of what a good high flow exhaust will provide. Why I may think there is more power is due to lack of hearing it and I am into the throttle more than I normally use. However I did some searching on cat-back comparissons and how that may effect the A/F curve. The more scavaging from low pressure exhaust at lower RPM without correcting the leaner the A/F curve is. There was a half decent article in 5.0 magazine that plotted the fuel ratio along with torque and Hp and was interesting to see that the stock program does with the air/fuel ratio. With the restrictive exhaust (stock) the A/F curve remains in the 14.7 to 15 then drops off at about 3000 rpm to the nominal 12, the pass through exhaust extended the 14.7 ratio out to 3300 rpm before dropping off (not much of an offset). They also had an interesting comparrison between the preditor tune and SCT tunes. After reading this article, perhaps a lower pressure exhaust does create more power, I just did not notice much of a difference when changing from the 04 cat-back to the SLP but did notice a difference after installing the 01 (only difference is not hearing the exhaust). Just for S&G's I will run at the track to see if there is a difference or not before reinstalling the SLP. I am sort of getting bored with the silence. If PA does pass the noise law I do have something to fall back on but sure hope it does not happen (the noise ordanance law is in the PA congress which would make it illegal to change the cat-back, muffler or rusty pipes to anything other than stock components on any motor vehicle which also includes motorcycles. They could use the PA inspecion as a means for enforcing it, but that can easily be bypassed if one still has the stock components. )

http://www.mustang50magazine.com/techarticles/m5lp_0605_2004_mustang_cobra_performance_test/index.html

ausie
06-18-2006, 03:42 PM
I have decided to take off the 01 exhaust and return back to the SLP Loudmouth. The only difference is better gas milage with the SLP (loosing over 40miles per tank of gas). Was hoping to hit the track before I remove the Ford exhaust but miss the exhaust note too much. If and when PA passes the HB 1330 I can always return back to the other, but might as well enjoy the SLP while I can. :thumbsup:

ausie
06-19-2006, 08:04 AM
Here is an update on the 01 exhaust. I tested the amount of probable back pressure on the pipes using the same method I did with the other. The recorded PSI reading was less than 0.5psi. The 01 exhaust is far better than the factory 04 exhaust since the 04 catback created a 1 psi pressure. Even with the SLP back in place, the boost guage is operating the same. It was my conservative driving which made me think there was an issue. :cool: Hopefully I will not get pulled over again since it is back on the car now.

ausie
06-20-2006, 06:38 AM
Stange as it is, there seems to be more power now than there was before I removed the SLP. Shortly after the re-install of the aftermarket cat-back I took a test drive. Since I do not normally watch the boost guage I decided to see if it still responds as it did with the 01 exhaust. Yep sure enough it did as well as ending up with a smoky tire response which was a bit unexpected. I must have gotten used to driving by sound and basically spent most of the time out of boost. :smack: :scratch: :crazy: :banghead: :doh2: At least I know what I will use if PA does pass the noise law but for the time being I would take advantage of the fact it has not. :thumbsup:

ausie
06-24-2006, 12:45 PM
After the SLP is back on, sounds great, better gas milage but now I want to take if off again. I still want to run the 01 exhaust at the track and compare the ET's to what I have logged with the SLP cat back. I do know that temperature and air density has some play in how the car will perform and I have been recording that as well. It may be better to get a controlled test performed with both exhausts on a dyno. I do like the sound but became fond of quiet sound as well since the supercharger whine with the 01 exhaust is more pronounced. The next time I take off the exhaust, I am tempted to start it up without the cat back installed (may be tempting but probably not a good thing to do.)

dewone
06-26-2006, 09:03 AM
On the fence are we. Do the dyno see whats best and go with the power, forget the sound :D. My exhaust didn't give me the sound I was looking for either :mad:. So I'm looking into the SLP's as well. Yes for the sound. After listening to a couple others with the SLP cat's It really doe's sound good. But I don't expect to sound exactlly like those cars due to my side pipes. I have dyno numbers with the present set up. Once I change cats will see what happens, and go from there. If the numbers come down. They come right back off. It must be a little bit of a hassel swapping so much though, so good luck, and hope you find the best for you. :thumbsup:

ausie
06-27-2006, 07:11 AM
Removing the cat-back once it is installed (aftermarket components) is not all that difficult since you can remove it as one single unit even though it came in 3 pieces. I am quite sure the SLP cat back creates more power than the stock plumbing 01 or 04. It is just that I have become used to the sound with the aftermarket kit that I end up hardly in the throttle. However with the 01 exhaust being more quiet I have been considerably more aggressive with the throttle probably because I cannot hear the exhaust as much. It is a state of mind :retard:. Just for fun I will change the exhaust back to the 01 just to get a few passes at the track. It may take an hour to swap the cat-back but it does make for a good debug tool if you cannot hear if you have a ping or other issues when driving. For instance, I did not realize how loud the noise from the transmission really is since I cannot hear the gears with the aftermarket cat-back on the car. The stock shifter is really noisy.

ausie
07-05-2006, 12:22 PM
On the fence are we. Do the dyno see whats best and go with the power, forget the sound :D. My exhaust didn't give me the sound I was looking for either :mad:. So I'm looking into the SLP's as well. Yes for the sound. After listening to a couple others with the SLP cat's It really doe's sound good. But I don't expect to sound exactlly like those cars due to my side pipes. I have dyno numbers with the present set up. Once I change cats will see what happens, and go from there. If the numbers come down. They come right back off. It must be a little bit of a hassel swapping so much though, so good luck, and hope you find the best for you. :thumbsup:
I guess I get bored and need something to work on while on vacation. Since I have recently serviced the Exploder (had to replace all of the 02 sensors, only really had to replace the single unit after the cats but why not all three. That sure made a difference in the performance of that slug.

I did it again, shortly after I took my sister out to a party on Saturday over the weekend I found it difficult to talk to her over the exhaust (had the windows open). I do love the sound of the SLP but there are times I do not want to hear it. One of those deals once you hear another car with a hot exhaust tone, you want the same, but then once you get it you wind up being the only one making the noise. There is nothing wrong with that but sometimes I want to have fun with my car without indicating to the world that I am going faster than I should be.

dewone
07-05-2006, 01:53 PM
I can relate to that, it's hard to sneak in un-noticed when your to loud. The being able to comunicate is yet another issue. Did you say turn left back there I couldn't hear you.... Hey on the bikes we got those helmets with intercoms.
But that might look funny at the McDonalds drive thru.:thumbsup:

ausie
07-08-2006, 08:54 AM
:rotf: wearing a helmet in a car when on the local streets would probably draw too much attention. I do have one for track use but that would probably get me pulled over moreso than the loud exhaust. I will be taking a long trip today with the 01 exhaust in place. I will see how my gas milage is effected since it is mostly highway.

ausie
07-10-2006, 07:42 AM
Here I go again...... This time the SLP is back on and there to stay.... My round trip took me 235miles total and that was it for the full tank. The last long trip I took nearly netted 300 miles and that was with the SLP on board and not so conservative driving either. Another thing I recently noticed is that with the more restrictive 01 exhaust (which would flow better than that of the 04 factory plumbing) the supercharger was almost as quiet. With a free flowing cat-back the supercharger just screams when you are on it. That is either good or bad ? but the more noise the better, right? At least I had a chance to remove the 2 years of road grime and tar from the exhaust.