[razordave]

Freebeard, what's in the photo? is that a box cavity?
NVM I found the anal probe thread with a box cavity.
The photo must be a Bonneville spoiler.

My partial boattail doesn't move at 70 mph so even if it's not doing anything for aero, I doubt it's doing anything negative so it stays for now at least.

I do need to do something with the muffler, it's 2 inches below the lowest point of the rest of the body.

I think I'm going to build a channel 3.5 inches up into the spare tire hump so I can raise the muffler 3" or so. that should give me some room to start on a diffuser. dependent on where the muffler ends up, I may cut the rear bumper to get the diffuser up to a good angle.

Any input for a diffuser that will keep my car usable at 120mph ish (assumed top speed) for when I get it onto a track (sebring is less than an hour away) and not too detrimental to aero efficiency?