i met a guy when i was in philly who has a nissan only performncae shop. he also has a machine shop with it. he makes custom parts for all of those engines i listed. he makes throttle body spacers, intake manifold spacers, new valves, crank sprockets, grounding kits, pullies. im just posting this because it is hard to find a lot of support for the sentras. the vq35/sr20 have it a lot easier. also, he dynos every part before he releases it. is anyone is interested, i think his site is wrptechnology.com