Re: a couple 86 Crown Vic questions
The proven formula for dual exhaust on box-body Crown Vics:
1) '86-'93 5.0 Mustang headers (factory or aftermarket)
2) '86-'93 5.0 Mustang H-pipe (again, factory or aftermarket, cat or no cat depending on budget, preferences, and local smog requirements)
3) Two Walker PN 43281 midpipes (trimming required; must buy flanges separately)
4) Stock '95 Caprice mufflers (2.25" in/2" out, offset/offset; Walker 21110/21111 or equivalent)
5) Stock Crown Vic tailpipes
- OR -
3) Two Maremont 339221 midpipes (flanges included)
4) Your choice of 2.5" in/out offset/offset oval mufflers
5) Dynomax 2.5" tailpipes for '95 Impala SS.
My old budget system consisted of lopping the exhaust off behind the cats, getting four 2.25" 45 degree bends and some straight piping, and two cheap 2.25" turbo mufflers with no tailpipes. It worked OK, but low-rpm engines REALLY prefer to have crossover pipes if at all possible.
For a cheap-ish wheel and tire upgrade, consider looking for '98-'02 Crown Vic police wheels. I scored a decent set with mostly-good 225/60/16 Goodyear RS-A (V-rated) tires for $200 including the correct lugnuts and centercaps; if tires aren't included, Kuhmo Ecsta ASX's (also V-rated) are comparatively inexpensive and work quite well.