I agree that every car is a bit different... I dunno.
Back in 1997 I had a 1991 LX hatch 5 speed, had an AOD rear w/ 3.27 gears, M&H G 60 15s, U/D pulleys, a cone filter, timing, smog delete, no screen in MAF, no sway bar, exhaust was original, except for straight pipes in place of the stock mufflers and the car ran a best of 13.42 @ 100 MPH. The guy that bought it from me put an off road H on it, with some Flowmasters, stock headers still, a week later and went back to the track but cold only muster a 13.6 but went 102 MPH though... I remember we were all buggin him cause it wouldn't hook to do a low 13 and beat the 13.42.
With this LX I have now, I ended up running 13.1 @ almost 103 MPH [stock motor & intakes - just bolt ons] with the stock H pipe and cats.
The car now has what I would consider a nice exhuast.. the Mac equal shorties still, an off road X pipe, and Magnaflow cat back. I keep putting off the new heads/intake install because I am hell bent on going to the track one more time just to see if the exhuast really made a difference.. power wise it is the only real change I made from before when I ran 102.74 MPH.
Actually.. I went back to the stock bored MAF [the detonation problem is GONE and car pulls nicer] and put a 6AL box on and gapped the plugs .060", & 5 W 30 synthetic vs 10W 30 non b4, too...
My suspension should be totally setup by tomorrow, and if so I may just go Saturday before I swap all this new crap. I'm envious of all you stock guys that are in the 13.0s - high 12s

and really wanted to join that club before the stuff went on.