im thinking either 3" or 2.5", for my setup. Is there any clearance rpoblems with a 3" I am also dropped 2 1/2 inches.
Well on mine I have 3 inch piping ran like rsr’s gtII, under the gastank with only 1 bend . I really havent had any problems with scraping and I’m lowered about 2 inches.
my greddy mX
prob upgrade to 3 inch and 3 inch dp later on the road
I have a 2.5" side exit exhaust with a 24" cherry bomb. I drew a pic for someone on here a while back, you can search if you like. I’m lowered on Neuspeed Race springs (2.5"ish) and Koni Yellows, I have clearance issues quite often, mostly speed bumps and pulling in and out of driveways.
I use a Thermal 3". 
Fits perfect. No clearence issues. No rattles on the shift linkage.
but now I am running a 4" open downpipe
^^ wow thats supra territory