If i get SA rocker arms do i need guideplates?and if i get NSA rocker arms do i need them?

 

NSA = Non-self-aligning ... Needs guides
SA = Self-aligning ... Does not need guides

 

which one do you think is better to use on a high HP motor NSA OR SA??

 

The HP of the motor shouldn't make a difference. But if I were running valve spring pressures significantly higher than stock I would probably use guide plates.

P.S. Aftermarket guide plates never seem to line up right on the LTx motors. It's best to use the GMPP plates. They are cheap and available from your dealer.

 

I agree, GMPP plates are awesome

You can probably get away with SA with a stock of mild cam
and stock or Lt4 springs. If you go with anything bigger, go NSA.
Agressive ramp rates and high spring pressures will break the little
tabs off SA rockers.

There are a few people around here who've learned that the hard way.