Engine Ford Racing gt-40x

Just to be clear, simply looking over gt40x heads isn't enough. They need a valve job.
If they haven't had that done, that will be about $250.

Certainly an improvement over the E7s but make sure you get what yo paid for.

I probably wouldn't use E streets. They will need work right out of the box, I believe they aren't for hydraulic roller cams.
Thus needing at least a spring change (and i'm not sure that's all they need).
If you can prove these x's are valve jobbed, they are priced fairly. I wouldn't give up on them. If he can't prove it, offer him $550.

You have a turbo on a stock block(?) right? You just need good heads in proper working condition. Having a higher or lower end set probably isn't going to change much in your case.

I tuned a on3 car with the Ford crate motor, e303 and GT40x heads. was ing scary as a passenger at 12psi. The car had an insane midrange and pulled all the way to 6300.

your VE table will need love. once you are done retuning you can look at the differences in the values to determine how much more airflow you achieved.

you have to sort of feel it out. I would roll into the throttle and keep it out of boost, [you could unhook the turbo intake pipe] and see what she wants at WOT NA then scale the boost VE with that % change.