I had Joe at Chicane on Thursday throw on a Bassani X-Pipe which didn't fit properly due to the Older cat design, so he removed the cats and hooked it up as an off road X-Pipe!!! Like I said on another thread, I can't stand the Raspy sound it makes now with my Borla Mufflers!!! Way to loud and Import car sounding to me!! My main concern that I discussed with him the following day is it seems like I lost a ton of HP and Torque and because my car is an automatic it acts like its unsure of when to shift!!! I think it lowered my over all rpm range and the car may not be working as hard, but the shift points, well the car seems like its unsure when to shift!!! Any one ever heard of this or experienced this??? Do I need tuning just to put a different exhaust on with my automatic car??? Would this help??? He said most likely I gained some HP in the higher Rpms but I definately lost a lot of Torque in the low end!!! Any one have stats on what kind of difference in HP and Torque they got at different RPMS with switching out the Stock H Pipe to a X-Pipe with cats or without???? With 3.08 gears I can't afford to lose Torque off the line!!! Also, I used to love to be able to break the tires loose between the speeds of 0 to 30 when flooring the accelerator and theres no way I can do this anymore with an Offroad X-Pipe!!! I'm confused, I thought I would gain HP and Torq through the whole RPM range!!!
It may have just moved the powerband up alittle. You will not lose any power from it. Alot of it is probably in your head too, you may have been expecting a sotp gain and didnt get it. Throw a different set of gears in it and that will solve that problem.
Dyno proven on 4.6 sohc engines at my buddies shop, car gains peak hp, but loses torque, this is why he suggests catted pipes for 4.6 guys. Doesn't help either that your gears are horrible for an automatic, goto 3.73's or maybe 3.90's. So you are spending alot of time in the torqueless section of the power band.
X-pipe = raspy, wet raspberry import sounding, no matter what brand. H-pipe = Classic deep muscle car tone, since that is what was used on all muscle cars from 'the era'. Also of note; Read up on the differences between X and H pipes. Alot of aftermarket companies, featuring 'newer' X-pipe designs, claim they flow better than H-pipes. Do the research for yourself, this is simply not so. I believe there was an article in last months Modified Mustangs, by Scott Hoag, who is extremely well-respected, who attested to this fact. You definitely lose some bottom end torque, without the cats. The back-pressure they create is actually good for something, believe it or not. No cats on my car, but I retained the aftermarket Mac catted pipe, and I may go back to it. I encountered a noticeable loss in low end torque, after losing the cats.
