ISP, SRT, PFS... I know they all know the 2jz very well, but it might cost a bit. Of those I have heard great things about ISP and PFS, however, I would only go to SRT for dyno tuning. People are starting to finally realize just because Mo at SRT can tune the snot out of a 2j, it doesn't mean SRT is great. Their customer service is crappy and their parts and services are over-priced.

Dave over at Function Tuned was also alright in finding some issues that a members n/a-t had. Wasn't the best as he mostly deals with 350z/g's but definitely sourced the problem and got it running better than any of us could.