XRQTOR

just a qk question one of you fellas sent me some info and it showed a performance upgrade for a 5.0L mustange same as my 5.0L i presume but it said that the gt40 heads were 2k (us) for the alloy and it said the cast heads are cheaper so what i want to know is what are the 11oo gt40 heads we use here in aus and if i put gt40 heads onto my basically stock car (exhaust only) with 1.72 rollers what power gain can i expect. cheers

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Blown Boss 377rwkw

"Its not the 300rwkw, its the instant V8 torque that kills things"

st00pid

Okay, from what i know the GT40 head's are an aftermarket aluminium job from SVO. The $1100 GT40"P" head's are a cast iron, money friendly production version of the GT40's, but may have different sized valves, combustion chamber size ect.

I also understand that if you're aiming for decent numbers an aftermarket, aluminium head like AFR's are more cost effective due to the future potential/ weight saving/ porting costs/ that the GT40P's carry.

EDXR8

The heads used on AU XR8 which you can buy for around $1000, are cast iron GT40P's. They aren't as good as the alloy GT40's or others like edelbrock etc but are still great value. On a stock engine, probably expect 10-20kw, but you really need to upgrade the intake to allow these heads to breath a bit.