hi guys here are the pics of the exhaust as promised, When i received the exhaust it was labeled wrong, the first thing that gave that away was the outlets didn't run parallel to eachother which they should, after reviewing flowmasters and summits design layout (and using a little bit of good old common sense). And the second reason, well the exhaust system just wouldn't fit properly with the existing stock hinges (which it should). So i changed the location of the inlet. With the new location of the inlet, everything makes sense and fits properly. (Pics are attached). Your right Casey the flowmaster 80 series exhaust system does come with 2.5" and 3.0" outlets (my outlets are 3.0") also there are two options for intermed pipes 3.0" and the other dampers down to 2.5" at the cat. Also Casey I bought a new distributor cap and rotor (Bosch) since out of all the parts I should maintain frequently i have not replaced the distrib cap and rotor as of yet. In the past 5 years since i have owned the car and I'm pretty sure my Dad (who was the original owner) didn't replace it either. So with that on the way, it may revive a few last ponies over the years. I'll install it tomorrow on Saturday, and tell you how it went. And another question for everyone, which gasoline grade do you guys run with your cars? Does anyone know the GM recommended fuel grade for a 1988 Trans Am 5.0L TPI? Is it 87 regular or 91 premium? Thanks again guys for all your help. I'll post soon to say if the distrib cap & rotor helped. (I hope it helps)

on my stock 86 with a 305 tpi i ran a 15.86 at 85mph with a 2.09 60'. when i added exhaust (exhaust cut out inplace of cat 3" to flow 80 series dual 2.5" out to 3.5" tips) after that everything else the same i ran a 15.400 at 86mph with a 2.06 60'. i could notice the difference after the exhaust and it showed on the track.

my car is designed to run on regular(87 octane) at 6 degrees advanced timing(stock setting) if you want to run premium you have to advance the timing or there will be no benefit. i am noy sure what to advance it to for 93 octane but i would like to know so i can do that myself.

my 80 series has full 3" in and out, its available just look.

I run 87 octance, that premium gasoline seems to burn much slower. If you run stock compression there really doesnt seem to be a need to run higher octane.

Maniak
Put some 1.6 ratio rockers on there, and a cam if you can afford it. The rockers are pretty cheap on Summit, and its a neat way of getting more lift inexpensively without taking the cam out. I had the stock LG4 cam that came out in 86 in my TPI and the engine sucked, i dont know why GM did that in 86. I put a L69 cam in and it really made a difference, if i had the choice again i would have put a cam in with much more lift. Hmmm...