Contact GTM for pricing and other info. They had a thread on this a while back, I'll go look for it.
GTM Motorsports*::*ENGINE INTERNALS*::*GTM 4.2 L Stroker kit-For the VQ35HR & VQ37VHR
GTM Motorsports*::*ENGINE INTERNALS*::*GTM 4.5 L Stroker kit-For the VQ35HR & VQ37VHR
'Bout $6K for parts only.
The pistons in these kits appear to be for Forced Induction applications (probably 8.5:1-ish compression.)