Quality EGT gauge and have the bung welded to the exhuast manifold (don't just drill and tap it). Good quality water temp gauge wouldn't hurt either. I think boost gauge goes without saying. Depending on your boost, you probably won't need an ignition upgrade till you pushing past 10-12 psi. You'll probably see some gains, but I'd suggest investing in keeping the motor in one piece first.
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Andy - Reinstated
Hybrid Forum Moderator
'06 Subaru Legacy Spec B - Stock, for now
'98 Civic EX - CTR headlights and grill, Kosei K1's, for sale
'90 240SX - SR20DET that will never get installed, project car.