OK, all differerent opinions, but more importantly, on differernt cars!
Some boots which work better on certain types of car, may be less effective on different cars.
Being as the OP has a B7 A4 quattro, it would be helpful to the OP if you could state your own car(s) when giving your opinion/experiences.
I'll nail my flag to the mast now, and give my opinions.
On my previous B6 S4, the OEM boots were ContiSportContact2s. These were an "OK" competent tyre, and would be a good boot to recommend as a "base point". What is good with them: rock-solid excellent high speed stability (particularly when heavily loaded at v-max on the A-bahns), consistent dry peformance from new to fully worn, very good cornering grip (high and low speed) with good on-the-limit feel and progressive break-away. What is OK (neither excellent, nor crap): wet weather performance (all round [cornering, traction, braking]), road noise. What is poor: on-the-limit traction and braking - particularly under heavy braking, they let go before you expect them, and the ABS activates when it really shouldn't be, and slow-speed around town comfort can be a little harsh. Didn't respond too well to personal tweaks to tyre pressures.
When worn, these were changed to Michelin Pilot Sport PS2s. IMHO, a much better tyre than the Contis. Extremely highly recommended. What's good: wet weather grip - absolutely superb. Considerably higher levels of wet corner grip in both low and high speed corners, with good, progressive feedback, and a predictable and controllable break away. Same impressive level of grip under extreme traction and braking. Consistent dry performance from new to worn out. Low speed comfort much better. High speed stability very good (on standard pressures, not as good as the Contis, but increase the pressure by about 8psi, and then on a par with the Conti). They respond well to personal tyre pressure tweaks, but maintain good overall stability at lower pressures. Quieter road noise than the Contis. Superb Customer Service from Michelin. What's OK: progressive drop-off in wet weather performance in line with tread wear. What's bad: nothing - absolutley nothing. A perfect ultra-high-performance tyre.
My current B7 RS4 came standard with Pirelli P-Zero Rossos. What an awful, shocking, $h!t tyre. Should never have been fitted to the RS4. IMHO, a lethal tyre. OK, the facts. What's good: nothing - there is absolutly no area where they perform
better than any other comparable tyre! What's OK: low speed dry cornering pretty good, but little "on-the-limit" feel, and they break away with little or no prior feedback, and also without any progression. High speed dry cornering similar to low speed cornering, but when reaching the limits become very unstable and twitchy, and no confidence in consistency of break point. Extreme dry traction and braking OK (maybe slightly better than the Conti, but not as good as the Mich). Extreme wet traction and braking again OK, again better than Conti, worse than Mich. Low and high speed ride comfort OK. What's bad: where do I start. Stability, when I got the car (brand new with new boots!), any kind of directional stability was non-existant. Cold tyre pressures were found to be about 4psi down on recommended, but correcting them mad no improvements. Talking to others on rs246, and they all experience the same instability. Pumped the tyres up to full load pressures, and a slight improvement in stability, but still noticeably shyte. Pumped pressures upto 50psi all round, again an improvement but still noticeable instability. Low and high speed cornering, let's just say scary - no confidence, no feedback, no consistency. The worst thing about them though is general wet weather traction and braking. Traction, 4-wheel wheelspin in the wet, in fourth gear (yup, from a quattro). Braking in the wet, no braking performace, ABS working overtime - absolutely fcuking lethal. Aquaplaning, complete aquaplaning at 40mph, again, fcuking lethal. Stability as the tyre wears is also a big problem - the more the tyre wears, the worse the stability is, to the extent that when they reach about 3½mm, you are constantly fighting the steering wheel with white knuckles to maintain any kind of stability. They become ultra sensitive to road camber changes, white lines and HGV ridges - this simply proves that they have an extremely weak carcass, and rely on the tread rubber for strength. Tyre wear. I don't usually comment on tyre wear, because this is extremely dependent on driving style, and I'm known to be quite hard on my tyres. However, from brand new, to the tread wear indicators in 4,500 miles - even I consider that utter shyte.
Conclusion on the Pirelli P-Zero: utter shyte, no lethal. Do NOT buy. NOT recommended. It's few redeeming factors are considerably outweighed buy it's attrocious performance in other areas.
Conclusion on the ContiSportContact2: recommended, particularly for heavy loads or high speed European touring.
Conclusion on the Michelin PilotSport PS2: extremely highly recommended, particularly for extreme wet weather performance, and comfort.
I can offer further comments for boots for slightly lighter front wheel drives, and can also explain the the ideal uses for directionals vs assymetrics, if you havn't all fallen asleep!
