I had a flowmaster series 40 on my old 2.5 4 cylinder S-10. With about 5 feet of 3 inch0 pipe behind that (yeah yeah I know its ricy well I got a mustang now, when I had the truck, it was cool) it sounded real good. The mellowist 4cylinder I have ever heard.
But with that muffler being the whole way back I don't know if it will sound good or not. very hard to say. Try increasing the size of the whole pipe then put a free flowing muffler on the back of that.
Keep it real and let me know how it sounds
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My 98 yellow stang
Mods:
Magnaflow cat-back