I won't know anything else about them unless/until I pull the engine. The car supposedly dynoed 450 @ 19 psi a while back. I will dyno to tune after I break in my clutch and get some sort of engine management installed - link or haltech. It runs super rich on the jwt chip and has had a bad clutch for a long time so to me it doesn't feel all that strong. They spool about the same as stock from what I remember of my old Z.