Header received. SLIGHTLY too "low", (close to LG), so...if you order a Mueller, get it 1 11/16, or even 3/4", but not MORE. It's pretty close in there fitting between the cowl and the LG crossplate. Course, if you put on 2 part CF gear, then that adds the clearance you'll need, and the 1 9/16" original measure will work just fine.
I tweaked mine just a skosh...pics show the evidence, but it will work just dandy!!!
I ran the thing, and YEEEE HAAA! OMG the power, the POWER....
Very sweet header... my coupler material worked just fine on it, too!

THank YOU Karl!!!!