I am in the process of buying my buddy's supra. The current turbo is a bit on the large side for me since I want a bit faster spool and I'm use to my sp61gt dbb turbo. You can check out the build on "thedave925" profile. He currently has a fully built motor with an old school Turbo Concepts t70 bolt-on turbo. I'm looking at getting something more in the 64-67mm range, but my question is, at which point should I go to a ball bearing turbo over a journal bearing turbo? What are the benefits of both and the downfalls (besides ball bearing costing more to rebuild)? And should I go to t4 or stick with a bolt-on? I will be doing some time attack and also some drag racing in the car next year so I need to find a turbo to suite these needs. I am looking to make between 500-550hp at around 18psi on 91 california pump gas daily and over 600 on race gas. What size turbos should I be looking at for this power range with quicker spool? And should I be going ball bearing or just using journal bearing? And I am not interested in a qsv. Any and all opinions are welcome