390 rear How good
 

My fd was auto, did a swap to manual. My mod are Power FC, 6 puck racing clutch carbon, short shifter. Right now i'm adding 1300 secondary and 1000 primary.precision intercooler and koyo rad...Stock twins. Now I have a 3.90 rear from the auto which i never swap because of the top end. which i like n feel. I'm going with a cusco lsd 2 way. Now my question is with the cusco lsd would my rear hold up or go with a t2 rear and go with a 4.10.rear.

Some info: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-much-can-stock-fd-differential-handle-630755/

1. Your injectors are ludicrous size for stock twins, even for most singles.
2. Top end? The 4.1 gears top out at 200 mph. How much more do you need? 4.1 will significantly feel better at any speed.

well the reason for the big injector. I'm aiming at a T70. True about what you said about the 4.1. Like my brother said where am i going to open the throttle that wide. 3.90 or 4.10 doesnt matter. to get a T2 alot cheaper. Guess I'm going with his saying. Thanks bro for your help

You would have a lot easier time just running 550cc or 850cc primaries and 1600cc secondaries.