most of the gains you get are from isolating the air filter away fromt he engine bay where it's hot. so what i'm saying is the MAF to fenderwell piping is what matters. do you want looks or performance more? the plastic densecharger kind don't heat up like the metal ones but they are "ugly" to most people. your 4.6 won't benefit much from a larger MAF/TB unless you're going power adder.
as for the exhuast, a catless system always sounds nastier (raspy, bad) than a catted midpipe. i've heard 2v and 4v with and without and even a 4v before and after within 30 minutes to compare. cats sound a lot better. they also rob power, but if you got the money for hi flo cats, why not be legal and sound better?
and LT's are win. :jeff: