how close to your 175 whp are you now? I mean, if you are at 172 then yeah, fuel management will probably put you at your goal.
the ideas that have been thrown out there are not Nissan specific, but rather fundamentals of the internal combustion engine. Fact is, that that your engine will make more power with a higher compression setup, whether you do that through pistons, or head gasket, or shaving the head, it doesn’t matter. You will never hit your goal and be “the first person to hit 175 na whp” in your car if you don’t think outside of the box and that might possibly mean talking to a machine shop, and shopping for pistons that will fit your engine, or will fit after it’s bored out. There is so much you can do, but again, if you are looking for the “bolt on Nismo head shaving kit” you aren’t going to find it.
I don’t want to get into what comes next, namely, can you hit your mark, on your budget, staying N/A. On a 4 banger, that will be very difficult because of the possible internal engine work required.
chris