GXP_Sturg

Just purchased my 06 about a month ago. It has a k&n conical filter and muffler delete. Car has 99,000 miles on it and already has had a trans replaced in it i have a system installed in the car that amp, sub, etc weighs around 120lbs in trunk. I ran it a week ago at local 1/8 mile track and it ran a best of 9.65@72. Im over 300lbs so ik thats part of the slower time but it just seemed to be more sluggish at the track then in the street. Also that was on 87 octane and im sure it needs the 100k tune up. But just curious of what could make it that much slower than what seems to be the normal for stock on these cars

severancej

Don't run anything but premium fuel. The lower octane gasoline it's causing a ton of knock that's retarding timing which lowers power.