What Heads?
 

I've read the most effective heads to use for my closed deck block would be Version 3. But when i've asked why (Valves?Valve angle?/Cam's?) i can't get a definitive answer. What year(s) are V3's, bug eye onwards?
I've been offered some 2005 std heads which i believe will bolt straight on, are these a good investment?
Thanks

you need to be a bit clearer about what you are trying to achieve...what MY car are you intending to run this engine on.

v3=MY97 a bugeye is a MY01-MY02

Closed deck were only 93-95 i thought? Anyway its from a 94, going onto a 94 WRX. so V3 is 97, any idea what differences there are on these heads as std compared to V1-V2?

I think all the sensors from the 05 heads would need adjusting and if the heads have avcs then your ecu won't be compatible. An aftermarket ecu may be needed

Steve

They're non AVCS. I'd maybe have to look into a different manifold and coil-pack set up but thats no major thing.
I just wondered if anyone knew like a "history" of the impreza head....?

version 3 heads will be fine to use with everything fitting straight on, the v1-v2 heads are hydraulic lifters, which are poo, the v3 will be solid and will require re shimming if you use them.
The 2005 heads will be more hassle than there worth, your current inlet manifold wont fit for starters and none of the wiring loom will be correct either.

The version 3-4 sti heads are the ones you want, they have the most aggressive cams and sodium filled exhaust valves, this is why they are preferred for the early cars.

Just to add you will at least require the map checking or ideally a remap to suit if your changing heads

Thank you very much thats what i was after! So V3 it is, oh and full remap will be carried out....:)