I have an '03 GT with cold air, ported intake, shifter, pro chamber and flows on street tires w/ stock gears. I ran 13.92 at 100 mph in the 1/4. In the 1/8, I ran 9.00's consistantly at 78 mph. I recently installed 4.10 gears & Nitto drag radials. I haven't tried in the 1/4 mile, but I have been down the 1/8 mile several times. My times got worse! Sixty foot times improved 2.3 to 2.124 & mph stayed the same but ET went up. What's up? Will I see an improvement in the 1/4 mile? I don't get it! I've tried 18-13 psi w/ no difference & I've tried different launch rpm... Any suggestions? Please let me know.

Jeff

have you ever tried pushing a car w/ flat tires?or riding a bike w/ low tire pressure?That's what it's like when you lower your tire pressure that much. On a 'racing slick' you're supposed to lower your tire pressure because the tire's sidewall should 'give', but on a 'drag radial', the tire has belts in the sidewall,which won't give. Raise your pressure back up to 28-30 PSI and this should help raise your MPH and lower your ET.  

dude,your way off.keep the tire pressurearound 15to18 p.s.i.thats where the drag radials work the best.

jw03gt,raise your launch rpm.now that you have 4.10s it will be alot easier to keep the car in its power band.launch the car around 2000rpm's at first and keep raising it 2 to 3hundred rpm's till you find your best launch.my guess is like 3000 to 3500 rpms.maybe even higher.pay attention to tire spin also.make sure to heat the d.r.'s good,spin them till you start to see smoke you shoul be hot enough then. good luck.

the car I drove w/ Nitto s, that's where it seemed to work for me, but then again, it only had about 310 RHP. If you were running a blower w/ say 450+HP you would probably need to lower it to what you said 15-18psi. The less HP you have, the more you can raise the tire pressure.  You do, though, need to build some heat in the Nitto's(burn-out).  

Thanks for your advice. Tried 30 psi - worked great. Unfortunately, worked too good. I heated the tires very well & left the line around 3,500rpm. Broke left axle. Broke the rotor off the hub. And ended up breaking the caliper... It's been very expen$ive. It's ok.. will be fixed soon. Will try again later once I have better axles.By the way, 60 foot went from 2.2 to 1.9

Well the reply you got from 7seven is going to be the right direction.

the other thing is ,are the new tires shorter in over height, that will

cause a difference too.

Good luck