Edelbrock lists a TES system for 86-90 5.0/5.7 T.P.I. w/ 3"slip on cat (part #6872). They do not list one for a 1991 TPI w/ single cat. But they do show one for 88-92 TBI with 2-1/4 cat.
Is there any reason the system for the 86-90 tpi w/ 3" cat, would not work on my 91? That is as long as I change the cat and rest of the exhaust to 3"?
I plan on a Catco replacement converter for the 3" system as well as a Flowmaster American Thunder 3" cat-back system.
I do not see any reason why this all would not work and bolt up together with no problems.
Anything I missed?

 

You should have no problems with your planned setup. There were some differences in the exhaust systems but if you are going to change the whole thing then just wait until you buy everything and then get it done all at one time.

I was running the same setup on mine before I went to the Edelbrock catback for a more factory look without those flashy tips on the Flowmaster.

BTW, spend the extra $$$ and get coated headers and Y-pipe, it is worth it in the long run.

-Ozzy