Does anyone knows more about the Hi-TECH Rom for 350z? How much and where can I get them?

http://www.webamuse.co.jp/z_cpu.html

 

Drop the zeroes, multiply by the currency conversion rate (8.56), and you'll get the rate for the ECU. It's not entirely accurate, but it's about what you should expect to pay for the unit.

Basically, they have three types, one that bypasses the speed governor, one that bypasses the speed governor and rev limiter, and I don't know what the last one is, as I don't know my kanji too well, but as an educated guess it might be an outright replacement ECU which can be reprogrammed.