head and h-pipe question

[ratrapp]

i have an 88 hatchback with a 5.0 and 5spd.the motor is out an 90 marquis with e6 heads.the car currently has flowtech equal length headers,typhoon intake,70mm edelbrock tb,mass air conversion,190 lph fuel pump,march a/c eliminator,mac cai.i need to replace all the rest of the exhaust and i am going with a dynomax 2&1/2 catback but would like your recommendations on a catted h pipe.also if changed to e7 heads and shaved them .020 or .030 and mildy ported the exhaust side would i feel any more power?also the car has a b303 cam.thanks