As for the downpipe you really can fit a 3" with alot of the a/c manifolds on the market. Take a look at my build thread, the manifold I used left alot of room for a 3".
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Don't bother giving me "rep", I won't return it and I think it is stupid.
Gracie Barra Clearwater
Gyms in Clearwater, St. Pete and Port Richey
pm me if you are interested in trying a free class at any of the gyms.