Is it a must to gasflow heads and get the chambers matched when fitting a 2.5 bottom end?

 

Depends what you want out of your set-up. For most people, no.

 

Well they are sti 3 heads .Bottom end has wiseco pistons only . So 420hp max approx probably only put 20g on for now? just want a fast road car no track monster.

 

Ahhh... right sorry. I assumed you meant Newage heads. Again, I do not think that porting those heads either is a pre-requiste for the type of power level you are looking at.

 

Ok mate thanks

 

good point

 

Looks like i'm several hundred pound better off!!

 

i never did for mine with v3 wrx heads, although i have a 16g on mine, so it was never going to make power high up anyway

it is making 300bhp at 4.5k rpm at the moment tho which is nice as hell to drive

 

if you funds allow ...do it as it as it will give you a much smoother revving engine , also save you doing it in the future as the engine is out now

 

So where is the best place to get it done? is it really needed ?

 

No... it is not needed for 420bhp, but that is not to say with ported heads it wouldnt be better.

 

Your right i'll get it done

 

I would agree that porting is not necessary for the power levels you are looking for. However, you will benefit from having the combustion chambers on the WRX heads opened up to matched the larger bore of the 257 shortblock. It is not absolutely necessary but does make the engine less prone to det and allow you to run more ignition in the mid range. It will also reduce your compression ratio slightly so you will need to run thinnner head gaskets to compensate.

Andy F charges £50 per head for this mod. I got Steve Whitson at SW Motorsport here in Scotland to do it for me for the same price.