I was thinking about porting my stock exhaust manifold and o2 housing before i upgrade turbo after i upgrade to a downpipe. Should I expect any gain from this? Will it hurt anything since im still running a small turbo? Porting the exhaust manifold is suppose to let the exhaust gasses exit faster, faster spool up? The o2 housing is suppose to let the exhaust flow out faster? Am I on the right track? Thanks everyone!