The best gearset for a street car is the Billet Straight cut (Spur) Synchromesh engagement gearset. This is a tried and proven product in Australia with approximately 30~35 sets currently installed and running in varous sr20 powered vehicles since 2002.
A new revision was introduced in early 2005 with a larger, more durable Nissan Skyline GTR type 24 spline input shaft and larger gears compared to the earlier version.
A gearbox like this is shotpeened and cryotreated they can support NA cars and circuit cars , high power beast making 450-500 hp.
If you are really intrested you can contact Gerard Chan @ PAR, he helped me out a while back he is a good dude and knows his stuff.