I just installed an Evo III 16g in my gvr4. Everything runs great, boost gauge holds at 15 pounds WOT, but at 5.5k it has a small stutter (engine just looses power, no noticeable sounds or anything) and then pulls slowly. I haven't held it to see if it will go to redline, kinda worried about harming anything. Can't figure out why it is doing this. I cleaned out the TB, checked all connections, seafoamed car, oil change, even switched out the wastegate actuator from my small 16 to see if that was the issue. Still the same problem.
Any help will be appreciated. I will do a boost leak test in the morning and post results.