28's your waste to much gas if you plan to run use the OS 28xz great power using a 2060 pipe you will get average 8min run time at TRCC and i was getting 9 but your clutch and tires is key. Also it puts a lot of stress on your drive train you will be replacing more frequently

Get JX21 or speed if your looking for cheap motor get the new OS21XZ replacing the vspec or a B5 Werks. Alphas are good too from the read but its drops off on the high side but our track is small you wont notice.