How much horsepower would i pick up from converting my tbi to tpi? If i did this would i have to change anything else in my car like the exhaust? My car is almost completly stock w/ a k & N filter, hypertech chip, high performance spark plugs and wires.

I have a small rivalry with a friend with TPI, we run almost identical setups save for a few parts,

16 inch IROC-Z rims vs 17 inch vette rims
Steel vs aluminum driveshaft
2.5 inch free flow cat + cat back and flowmaster vs his 3 inch
1.6 rocker arms vs 1.5 rocker arms

He can run a best of 15.1 while I run a 15.4...

We ran on a dyno prior to my 1.6 rocker arms mod and he had 280 ft/lb vs my 258 ft/lb of torque and he pulled a 180 HP and I had 158 HP.

I'm pretty sure the rocker arms made a serious improvement on my part, probably running around 270 ft/lb of torque at the rear wheels now.

I dunno if 3 tenths is worth the whole tpi change for you... the worst part being the fuel pump change and I've done one already... not a fun job.

What arew the other constants? Are you running the same heads as your friend? What about cams or gears? I am not doughting ya just curious.

in factory trim tpi has a few very noticable things over tbi. 1. cam, 2. heads, 3. more developed intake system.
for the several hundred dollars of a change over there is a lto you can do to tbi to more than make up the difference. also, when it comes time to go beyond stock tpi parts, they are expensive.

later
tim