i own a 95wrx ra
Does any one know if it is possible to fit the later (97 wrx or sti) heads as mine may have cracked. What are the differences - cams, valves size, tappets, will the coil packs fit as well as inlet manifold etc.How can you tell the differences between various heads uk, jap sti etc. Need as much tech info as possible please help.

 

Heads from a 97 will fit without any modifications. Just make sure you get the rocker covers too.
Cam specs may be different on an STI, but other than that, the heads are very similar, and any differences would not be worth worrying about.

 

whats the differences between the rocker covers anyway, if there are any. Luckly the pair of heads are complete with covers & cam pulleys as well. Just a point though im sure i read a thread some time ago were the inlet manifold had to be extended to fit and some other mods too? Also if the cams are different (the profiles) is there a change in the power at a certain rev band ie power would be stronger from 3000rpm to 6000rpm. Would the tappets be solid or still hydraulic in the 97 head.

 

The later solid lifter camshafts have biggger bearing journals, so need the matching cam covers.
All other bits are the same..eg pulleys