I would never run ANY head out of the box without my machinist checking them over first.

I have Stealths but they have different springs, locks and retainers. They have over 5,700 miles, lots of dragstrip passes and still run great.

We make 600 n/a and ran a 150 shot through them some last year. We recently jetted up to a 200 shot and haven't been able to get a clean pass at the track.

That said, a buddy bought Trickflow 240's and loves them!