I have an 89 gtus with a header/presilencer and a cat-back. It has 147,000 miles, but the compression is still 85 psi on all chambers (tested it today). I also set the timing perfect. But I get about 12 seconds going to 60 on a 50 degree day ona flat land. My question is, why? The power band doesn't have any power gaps (like the actuators not opening). It just doesn't go very fast. Could it be dirty injectors? A bad sensor somewhere? Could low trans fluid do it?

I can think of a thousand things, but does anyone know the most likely problem?

oh yeah, the bac is pretty crappy, but that wouldn't do it would it?

one more thing: I'm at 1 mile above sea level

Bac would not cause that. Hmmm cats is not an issue nor is compression.... Are u sure the VDI is doing its magic? Well whatever those s5 do... 0-60 in 12secs is way to slow, my car(n/a) did 0-60 in about 7 flat stock.

does no one have any ideas? I would really like to hear your thoughts on this.

All I could think was cats. Mine was doing that, and it turns out a piece of that ceramic **** was stuck in the exhaust. If that's not it, I'd recommend taking it to a local shop or Mazda dealership and getting diagnostics done on it, unless you've got a whole lot of time on your hands.

thats weird, last week i got on my car from a dead stop and it was about 11 secs 0-60, i was pissed cause i still dont know why it did that (it did the same thing all night after i tried a few more 0-60 times) and im a good driver, i had my friend with me who always dogs my car and hes like i told you it was slow,lol he was just kidding cause he knew something was wrong too? neither one of us knows but every day after that night i got on it and my 0-6- time with my buddies g-tech measured a 7.1 0-60 time? and thats only because of my basic mods, it was 7.7 seconds 0-6- before i did a few things to it,

Leaking or dirty injectors would be a noticeable problem..the power would kinda bump as you accelerate...so thats probably not it...dirty airfilter is a possibility...with that cone style filter it should be really easy to clean...um, what about tires? lots of wheelspin? my NA did 0 to 60 in 12sec too...but it laid 1st gear and the first half of 2nd out on the pavement before it got traction(damn 185 tires!)....and of course, i mean no disrespect but a lot could be driver...learn where the best shiftpoints are and nail it..dont be afraid of 9K,lol...I can't think of much else...

Yeah, I found that peeling out is worse. I just let the clutch in fast, but not enough to peel the tires (I tried peeling first, but that was worse). It never drops below 2500 and I take it to redline and shift to second instantly. Second tops out at 60 (pretty convenient huh?). There's only one shift in there, and the launch seems pretty good to me. I don't think even a world class driver could break the 10's in my car. It just doesn't feel powerful enough. Wheelspin is never a problem, it's an NA remember?

Actually, I found that shifting at 6000 brought me down close to 11, so does that mean there's a high end problem? I could double check the VDI, but I'm pretty sure it's working great.

Also, I've given a ride to a friend with an 87, who got 60 in 7.8, and he said my car pulled harder. Strange....