I have a LS/VTEC.
I have a full 3" exhaust system and a ramhorn manifold.

If I connect a Garrett T28 turbo (from a 200sx) with an external wastegate,
do you it will be OK even at high rpms at 10 psi ?

Or is it risky to use it in case of high EGTs.

 

I don't see why it wouldn't be ok, lots of people use t28's

 

maybe on higher pressures, because of backpressure..

 

You might just have early spool with it no top end, good dd turbo
but I've never used a t28 so idk exact boost range

 

you will have no problems on such a small turbo, even at high RPM's.
just make sure the tune on the motor is good.