I'm planing on returboing my msp! The Guy that had it before me wrecked it and didn't replace the Turbo kit! So I'm wondering what would be the best brand of Turbo And what should run! I'm currently building a motor to handle hopefully 500hp!

 

You need to read this: https://www.mazdaforum.com/forum/new...an-mp5t-19356/
This guy recently changed his turbo set-up later in the read. You may want to click on his name and send him a private message.
My 2 cents worth: transmission won't handle 500 HP---serious rebuilding here.