OK. Despite having done countless hours of research and questioning mechanics, I am still willfully ignorant about this wonderous machine. I have done following mods, well had them done professionally. Jlt Cold air, steeda u\d pulleys, sct sf3 (93 octane canned tune from jlt), frpp equal length Shorties, upr o\r x, pypes muffler delete (aka straight pipes), and chrome 20's w\ nitro 555. Obviously I have spent money on the right mods. But somehow I can't beat a stock car from 0 to 80. I was shocked when we timed yesterday. I got the tuner out and adjusted wide open fuel to air mix. That helped very little. My question is this... did I lose power by adding headers to straight pipes? Or is it the crappy tune? I guess I need back pressure? I know I need a tune! Any suggestions? Thanks once again from a humble learner in ky.

 

I'd certainly point a finger at the tune for starters. But I'd hold off in considering the straight pipes as the 2nd culprit until you have a tune that is right for your mods. I really doubt the canned tune is doing you and your mods justice. Even the canned tuned on a car with only a CAI & tune sucks compared to the custom tunes.

As far as the exhaust, I don't think it's much of an issue other than a bit of torque in the lower (MAYBE throughout) RPM range.

 

I would look at the tune first as well. I hate to tell you this but you wasted your money on shorties, they don't really help performance just sound. and those 20's are killing you as well.

 

Yup, the shorties won't net you much. And I agree with everyone else, the tune has to take into account every else that isn't stock. And of course, the 20's will hurt ya in acceleration.

 

What you made up with the UDP's and aluminum DS you probably lost with the 20's...

 

3 words. It's the tune

 

Thanks mfers. I am grateful for your help. Here is what I don't understand. First the wheels...I made sure to keepthe same overall diameter\circumference as the factory 17s. I.e. bigger wheel, smaller tire. Mainly to keep an accurate speedometer and odometer. How is that hurting me? Second, Shorties...I bought them on mf. Forum. After I did some back n forth posts inquiring about the effects. It was my understanding that a better overall air flow will help in the long run. I plan on forced induction the first of next year. Luckily, the price was right ($125) on frpp headers, and now axle back mufflers I bought today from forum for ($100) I guess I will get w/ brenspeed for a tune for MY car specific. Someone let me know. Thanks again in ky.

 

Sadly, shorties are a waste of money. If FI is truly in your future, LT's is the only way to go.

As others have said, your tune is ***. Get one from Bama, Brenspeed or another vendor mentioned in these forums.

Did you happen to weigh your wheels? I bet your chrome dipped 20s are very heavy and are slowing you down A LOT. I have some "light weight" 20s and they are still fairly heavy at 55lbs. Your stock 17s were only 45-50lbs, your new 20s are easily 65+. I also doubt the udp's made up for the new wheels.

 

Like bmr said, you added a pretty good amount of unsprung weight. Lighter wheels, gears and a decent tune will put you where you're thinking you should be.

 

im surprised no one pointed this out.

he said stock car, but never specified the details. just because a cars stock doesn't mean they all come from the factory with the same options/equipment.

IE: gears. if hes rolling say 3.31 and hes going against a car with say 3.55 or maybe even a newer gt say 2010 with 3.73 that will make a difference in the outcome.