IME Audis are pretty consistent, namely, hard. Have been since forever. It's a feature.
rlarsen462- A looong-winded response follows.
Some sorta-random thoughts:
-Work one, small *limited* area until you find what works
-When applying pressure, don't overcome the pad's rotation to where it merely "jiggles"
-Prime the pads properly, esp. with M105
-Repeating- work small, and I mean *SMALL* areas
-Don't overwork the M105 to where it's hard to buff off
-Clean the pad *VERY* frequently, as in..."what, not again...sheesh!"-frequently
-Yeah, the M105 should finish out pretty well on Audi clear. I wouldn't go so far as to say LSP-ready (see it under a SunGun and you'd know what I mean) but it won't look messed up either
-Failure to clean the pads frequently/well enough *will* result in M105 leaving things looking messed up
-Spritzing with M34 can help with marring-free buffing of M105 residue
-You shouldn't need to/want to switch to M205 until things look mighty nice (after just the M105)
-Do the final M105 passes (yeah, passes *plural*) with a milder pad and less appllied pressure and buff off the residue even more carefully after those passes
-If you want to try Surbufs I'd use smallish ones (not 6") even though you don't apply a whole lotta pressure with those
-Something you don't want to hear: Audis oughta come with a Flex 3401 in the trunk. You might need one of those, or a rotary, for timely correction. But things can go *wrong* with those very fast too, compared to with the PC.
I don't mean to kick a guy when he's down, and I hope this doesn't sound insufferably offensive (and after-the-fact), but I'll risk it in an attempt to save you future frustration- you shouldn't spend hours and hours doing *anything* that's not working properly. Work a single one-foot-square section (or even smaller) and you can go through a whole lotta trial-and-error in an hour or so. Though it might take an hour or so to do a small area. It used to be somewhat common for somebody to spend an hour per panel, or *more*, doing correction on hard cleaer via PC. M105 can speed that up, but only so much.
If you think the M105 is causing problems, look at those problems and try to analyze them. Do they look like they're from when you wiped off the M105 after buffing, or from when you were machine polishing the area?
M105 shouldn't cause "damage"...products that were good for use on Audis *before* M105 came out (e.g., 1Z Pasta Intensiv) sure were risky like that though! So hey, it could be worse
On the SurBufs, note that no less an expert than
Kevin Brown has said that they're best left to people with considerable experience. Things can potentially go wrong faster and worse with those than with foam pads. In this particular case, I'd think twice.
I've done this stuff on *very* hard clear with M105/M205 and the PC/4" approach. It *can* be done and it's not magic, or voodoo, or some mystical art; it's just abrading paint until it's smooth and level. I mention that to suggest a calmly objective, pragmatic mindset.