This is taken from the April, 2008 issue of GM High Tech performance. ET reduction and MPH gain is for 1/4 mile track.

SLP Air Box Lid:
$99, 10 RWHP, -0.1 ET, +1-2 MPH, easy

QTP Exhaust Cutout:
$45, 12 RWHP, -0.1 ET, +1-2 MPH, hard

SLP Off-road Y-pipe"
$299, 8 RWHP, -0.05 ET, +1 MPH, medium

ASP Underdrive Pulleys:
$269, 8 RWHP, -0.05 to -0.1 ET, +1 MPH, medium

SLP Ram Air:
$169, 5 RWHP, -0.05 ET, +1-2 MPH, medium

Hooker Headers
$349, 20 RWHP, -0.2 ET, +2-3 MPH, hard

Drag Radials:
$400, 0 RWHP, -0.3 ET, +1 MPH, hard (easy for tire guy)

Random Tech Catback:
$399, 15 RWHP, -0.05 to -0.1 ET, +1 MPH, medium

Nitrous Express Wet Kit:
$609, 125 RWHP, -1.0 ET, +10MPH, hard

Yank Torque converter
$799, 0 RWHP, -0.5 ET, +1-2 MPH, hard

Meziere Electric water Pump
$599, 10 RWHP, 0.1 ET, +1 MPH, medium

 

just thought id add. all those times go to 2.45 sec off ur quarter mile time. Which is actually plausible i think. i dont think any of these are over zealous times

 

You could also divide the price by the HP or ET improvement & get the cost per HP or or the tenth/sec, and then see which has the most bang for the buck.

 

not a bad way to nearly double the hp