I have a picked up a aftermarket set of PnP'ed OEM headers, but I am not so sure I like what was done. It looks like everything was just gasket matched with the maximum material removed. Many people talk about how it is so important to keep the stock inner diameter of the up-pipe to improve spool, but isnt this sort of porting going against that theory? I think I may do the following with a another set of stock headers i have laying around.
-Port match headers to match the heads.
-Remove any internal casting marks.
-Maybe polish the exits of the pipes.
-Light port on the entrance of each of the pipes.
Tell me what you think.