odysseus said:
Yeah Marine, we all know it . . . .you're car is simply BADASS!

I have a feeling you're not stopping there, after Pete introduces his ESC for another 80+RWHP. That would put you in V territory!
The mods Pete did to those headers, helped quite a bit, I suspect. You're sitting somewhere around 40 to 45 over stock. ~300 HP out of a V6 with only exhaust and intake mods. Pretty amazing. I wish Lund had made them for the 3.2L car when it was being produced!
Marine's also running higher "useable" RWHP and torque in the lower and mid-range RPM band if you look at Marine's Dynameter run and that is a HUGE DIFFERENCE that has been overlooked aside from the tire RPM baseline issue.
He's not cooking his rear differential at 6000 RPM's to generate the 250 RWHP that he is getting from the headers and that is a huge difference.
Bottom line is that 250 RWHP in the RPM midrange is far more friendlier to that 3.6 CTS differential than 250 RWHP at 6000 RPM's and a new differential after you shatter that sloppy sand cast aluminum rear-end case. Been there, seen it; done it!
Bottom line is that he doesn't need a supercharger because the rear differential won't support the additional torque.
If I had his dual intake plenum and cylinder heads for 2 weeks to work with; I would have him at 300 plus RWHP and it would be totally stealth, undetectable and not jeopardize his warranty as a supercharger would.
Anyway, the CTS differential won't support much more than 300 RWHP as V owners are already on there 3 Getrag rear's and we're only running 318 to 323 RWHP "bone stock". And you want to mod that????
Marine is sitting on about 250 RWHP in a very useable low-midrange RPM band and that is the key difference. He's not heating up his tranny and rear differential to generate those numbers.
We can get him to 300 RWHP with just "reworking" the dual intake plenum, TB and cylinder heads and then I would cap him off unless he want's to invest $6000 in a bullet-proof rear differential, because the OEM differential will be "saw-dust" once you break the 320 RWHP mark at the 6000 RPM band. And that is an unshakable fact gentlemen.
ps: "reworking" the above means that we won't tell you how we do it. And it also means that if you sell Cadillacs, we don't cryogenically treat it, buy it from China; nor do we have a a Cadillac mechanic chained up in the service area with 27 years of Cadillac dealership experience of working on front wheel drive Northstar engines "cookbooking" the recipe for us.
Good day, happy holidays & safe motoring to all - Pete
Cadillac MotorSports, Ltd
[email protected]***********************