In the not so distant future i plan on switching to a 2.5l block in my 04 wrx. I have searched and asked people i know but i keep getting mixed results, so ill ask you guys. Some people have told me to have the heads ported and polished and get new valves, springs, retainers etc. in order to keep the heads from floating and to increase the top end and redline. But i thought that the WRX heads flowed pretty well and i dont want to have a full top end wrx. I am interested in the higher redline. If you guys could weigh in i would greatly appreciate it. all the people i know have getten me pretty confused about the best way to go.

 

a higher rev limit seems kinda pointless to me if your powerband isnt at the top of the rpm range...

 

Check out Axis Racing, Craford Performance, and cobb Tuning. they all offer what you want in the way of head work. For a stock 2.5 I wouldn't do any head work. If you go with a 2.5 with pistons, rod etc... I would look into it. do I search for the above shops they are all very good. As was already said I would raise the rev's for no reason. hehe

 

AVCS...doooo iiiiittttt.

 

people say to use wrx heads, build the heads with a good valve train set up but honestly nothing really changes but you're redline and to second jwrx it's pointless to increase redline without having topend... kind of an oxymoron there. but avcs is the way to go.. you'll enjoy it much more unless you want to launch your car at 9k revs and have hella topend power...

 

Yeah, avcs is the way to go. If you want top end performance flow becomes a big deal so port and polish while def. make a difference. As far as the dollar/hp ratio goes it's also going to cost you. I personally won't crack into the internals unless I was getting everything done (i.e. pistons, rods, valves, cams, etc...) but that's just me. It'll save you money in the long run and if your turbo accomodates with boost production you'll be able to crank it up a bit with the increased security. If you want to get better top end without the internal work get a bigger throttle body (or bore it), intake manifold and tumber deletes. Silicon hoses and Y will also give a little extra in that dept. Hope that helps a little.

 

I figured as much about using the regular heads. I did think though that you had to have STI heads for the AVCS? I may be mistaken but, how do you go about getting the AVCS?

 

You can get a forester xt long block, and then have your ecu reflashed to utilize the AVCS. Check out gruppe-s they almost always have cheap motors for sale.