Question on Headers
 

What kind of gains can I look to see from installing Mazdatrix headers and a straight pipe (instead of the presilencer) on my stock na 87 rx-7?

bump

I am just guessing, but I would say you would probably get somewhere around 15-20 hp.? Also I think you would proabbly not actualy FEEl the power as much as you would notice that it would just realy pull easily and smoothly past redline to past 7500. Th reason for this is because it can get rid of teh exhaust faster. Right now it might feel as if past redline it get bumpy and isn't realy wanting to pull but instead your pusing, I think this would go away with the pipe.


CJG

I ran this type of set up. So the header then a straight pipe and Y to each muffler. This will give you more torque. If you are trying to achieve top end, run a true dual exhaust.(loud) Or 2 small pre-silencers would quiet things down.

A straight pipe would be QUITE loud and obnoxious for street use, but I am not sure what your intent for the car is (I currently have straight pipes on my NA, and will make a video/audio clip if you wish). Bolting up the RB header and swapping out the exhaust to something a little more free-flowing will provide noticeable power. It's cheap, easy, and you WILL like it. :D