I'm running Keisler 1 7/8 headers on a B engine in a Challenger with a Keisler 5 speed. Front suspension is set slightly lower than stock.

When I first got everything installed they were a little low. When I shimmed up the gearbox to dial in the driveline angle they were OK. The collectors still pointed down a bit more than they should have which made the curves into the X pipe a little low. Those pipes got a few bangs on broken up roads... I learned to check my favorite country blacktops for serious winter damage before the first good run in the spring.

Anyhow I talked to TTI about the collectors and wound up buying some loose flanges and making my own. I got the exhaust installed as "high and tight" as possible with the collector slips loose from the flanges. I tacked the flanges with the system installed on the car then pulled them off for a full weld. I wish I had done this at the start.

On the driveline angle deal, I would think it would be possible (if necessary) to adjust the pinion angle with shims and carry the adjustment forward to allow you to shim the transmission higher for header clearance and still keep acceptable driveline angles. I've never tried this however.