Since you're in AZ, I'll tell you to do the same thing I did. Get the Fast Intentions Long Tube Headers + CBE. Sinze AZ has no emissions laws you dont have to worry about a sniffer test. That setup + install will run you ~ $2800ish. Sell the Nismo exhaust, add the total you bring in off of that plus the $200 leftover from your original 3k and get a tune. That's the best you'll be able to do with 3k.
I agree the best way to get decent HP out of the Z is to go FI, but on a 3k budget that's just not possible. You're looking at 10k at least to go FI. Not to
maintain FI.
And in the end, you're
still going FI in a manner of speaking.
