My question is if you do longtubes and eliminate the cats will the car run rich or lean. Cause i just did mine and my car seems to be smooking a little i think it is running rich. My gas mileage sucks now and i can smell gas from inside the car. I havent yet tuned it for the longtubes and cat delete but i have a regular pcm4less tune for my gears converter and coldair. If i get a tune for the headers will it actually make a big difference. Thanks

 

You don't need a tune for long tube headers. Now that the cat has been deleted, your exhaust is going to have a more obnoxious smell to it. But if your gas mileage has decresed and the gas smell is very overbearing, you might have issues going on elsewhere. I would make sure you don't have any exhaust leaks before the 02 sensors and that you may have not disturbed anything else during the install. How is the car running otherwise, any other symptoms? Do you have an SES light?

 

Actually the car has a little shake to it like a miss but shows no ses light . My freind with a snapon scaner said that everything is good right tps reading o2 is reading right map is good but i think it might be a iac valve. I had this shake before the header install so i am leading to that. My freind also said that the smell i am getting could be a leaky injector.

 

If I'm not mistaken, IF you have an exhaust leak before the o2's, they will compensate by adding fuel, you could disconnect the o2's and run the car in open loop and see if it runs leaner. If it does than maybe you have an exhaust leak or you may have bad o2's.

 

I haven't worked with a Snap-On scanner in years so I cannot recall their functions, but are they capable of plotting cylinder misfires? If so, did you record any?

 

i think theres something to gain with a tune after lt's. Ive read articles in gmhtp where they did this on cars and had small gains. (5-8hp)