The stock O2 housing is so good could an external dump may not really help performance. Also, are you ready to cut your front plastic bumper undercovering? If you don't I'm sure it will burn through. This undercovering helps your car be more aerodynamic. Also get ready to remove your radiator to do this job.

If you get your exhaust manifold, and O2 housing Jet hot coated I'm sure this will make a drastic difference to underhood temperatures. If you go so far to even get the downpipe done I'm sure it would help even more.