does backpressure affect top speed?

[strodda]

on the way to work this morning i wanted to see how fast i could go, but it seemed to go nowhere after 110. i assumed if anything i'd go faster since i got the headers and cat. i thought lowering backpressure only decreased lowend torque. ive gone 120 before when all i had was an intake and exhaust, so whats the deal?

[delsolsi]

A few idea's I can think of are,
Bad tank of gas.
Your car needs a tune up.
You were going into a head wind.
Have you added new wheels and/or tires? If so are they hevier and/or taller in over all diameter than what you had previously?
Where you going up hill, or down hill on the previous run?
Have you done anything to make your car heavier, like adding a big stereo system?
Was it hotter out on your last run than your previous run? Colder air means more power.

[delsolsi]

Also if your going those speeds on public roads, please be aware of the consequences to yourself and other's. I used to drive that fast all the time, I don't anymore because I ended up getting busted for reckless driving and go senteced to 10 days in jail plus a big fine and a very stiff probation.

[strodda]

well, both times i had the same rims/tires on, and no real wind. it was always on flat land and ive had the same system. i am always cautious, i only do this early mornings going to work(530am), and today was saturday so i saw about 2 cars on this particular highway... or late at night(after midnight).
im gonna do it again tomorrow since its sunday, so even less people will be up. ill see what i can do. but i guess its no big deal, how often can i need to go over 100 anyways...