Very Slow At Low End...?

[Bohemiangod]

So my car is acting very slow at low end. At high end it feels nice and strong but im pulling 8.34 0-60 times in my NA. That seems way to high. I have some mods to it but i have yet to update the ECU. Could this be why its not operating well?

[evildky]

kinda of a vague problem, how is the idle quality? and recent "mods"? auto or 5 speed? and I assume you are using a g-tech? and if so had you tested it before the problem ocoured?

[Bohemiangod]

Ok heres some more info. Yes it is a G-Tech. The first time i had used it i had huge holes in my muffler causing no back pressure but one of my injector connections was also unplugged. I ran a 7.3 at that time. The mods done are stainless steel headers, underdrive pulley set, cat back exhaust, no cats, and my idle is now at ~900 when before my IACV had a broken shutter and I was idling at 1500+. I figure even with the back pressure, I should be running faster now with the injector problem fixed and such. Even still, 7.3 seems kinda highish. Then again, I dont know what i should be expecting out my car.

EDIT: It is a 5 - speed and when my friend ran it for me i heard a rattling noise. Didnt know if it was the exhaust or what though.