View Full Version : Need advice on emissions testing for Cobra without cats

04-30-2008, 10:31 PM
I am in the process of trying to purchase a 2004 Cobra convertible with 33,358 miles on it. It is modified, but having not seen the car yet, I can't say what all has been done to it yet. The seller claims 550 RWHP and says it out ran a new Z06 by two car lengths during a 20-110 MPH run on the Interstate a week ago. It might take 550 RWHP for a car that is 600+ pounds heavier and less aerodynamic than a C6 Z06 to pull on it like that. Anyway, the car has an offroad X-pipe, Bassani exhaust, pulley, and who knows what else. Cosmetically, the car is in mint, showroom condition inside and out, so it's obviously been well taken care of. Also, the clean, one-owner CarFax shows that it was registered every year in an area (D.C. metro) where an annual emissions test is required. The car does not have catalytic converters. With that background, here is my concern: I need for this vehicle to pass the federal emissions test in order for me to register and drive it in my state. The test consists of the OBD plug-in for a half minute or so, and a visual undercarriage inspection to confirm that the cats are there. My thoughts are: (1) I can have a pair of new cats welded between the mid-pipes and the X pipe to address the emissions issue, but the OBD test might fail if/when the CEL comes on. In my mind, the CEL will come on because the computer won't be able to adjust for the sudden increase in backpressure caused by the presence of the cats. (2) I can attempt to pass the emissions test as is, but even if the OBD plug-in part of the test passes, it would fail the visual undercarriage inspection because the cats would be missing.

How do other Cobra owners with modifications (including X pipe and no cats) deal with the annual emissions test? Am I headed down an expensive rabbit trail if I have to pay $400+ for a pair of cats and the installation (welding), plus $$$ for a dyno tune in order to bring everything back into normal operating range for optimum performance/fuel economy/emissions? Is there an inexpensive and easy method for dealing with the annual emissions test while at the same time driving year-round without the cats? Clearly, the cats have to be there one day a year when I go to have the test done. I'm wondering how other owners handle this hassle. If the cats have to be welded, that does not sound like something a shadetree mechanic is going to be able to do in his driveway with a set of sockets. Also, if this car is tuned for 500+ RWP, is there a set of cats in existence that will stand up to that much power for 40,000+ miles, or will I be going through a set of these every 15,000 to 20,000 miles or so?

Thanks for your input!

05-01-2008, 12:48 PM
As for the cats I would put in high flow cats and leave them. There is not a huge gain from high flow cats to NO cats at that power range. Then you can just get the car tune once and be done with it.:thumbsup:

05-01-2008, 02:51 PM
Might be easier if we knew what state you're in.
Check with your state to see if they have collector's plates. Ohio does and the Cobra qualifies. If you have these plates, no test is needed.

If it were me... and it was at one time.. I'd go with the hi-flo cats. HP loss is minimal and you might even pick up a couple lbs of torque.

05-24-2008, 02:09 PM
i live in rhode island and have the "HIGH FLOW"cats. i pass the emissions test every year