Re: How much meat is in the EF xr8 heads?
Hmm Is it just me, or does that look like its intended for carb rather than efi ?
I'd try a quick search on "professional products" I seem to remember them being mentioned here before, but can't remember good or bad.
A better intake will yield gains, but the E-7's are fairly well regarded as best used for anchors. Ideally, I would look at trying for head work and intake, or new heads and intake. You could also look for AU intake manifold's (explorer) as another option that might be low cost, and reasonable results ( especially if keeping E7's ).
Unfortunately, I have no idea as to how much porting is possible on the E7's.