Because I've had a 99 for 4.5 years I'm prejudiced. I made a few mods to mine and it dyno'd at 297.5 RWHP and 295 RWTQ -- and that was simply a Dynomax X-pipe and cat backs. Since then, I've added an 80 mm C&L MAF w/
K&N filter and
BBK 75mm twin throttlebody. So I'm guessing I'm making more than 297.5 RWHP now, but I haven't dyno'd it since the add ons. It also has a new 3.73:1 rear end.
IMHO it's largely a matter of luck. I've heard of complaints from both 99 and 01 owners. Mine has held up great. I set it up for driving on road courses with a full Kenny Brown
suspension system. I've been running it at instructional open track events, primarily at Summit Point WV, but also at VIR with SVTOA, NASA and Car Guys for the last three years. Changing the rear end allowed me to run both courses in 3rd and 4th gears vice 2nd and 3rd with the stock 3.27:1. Summit Point's main track has a 3,000 ft front straight and I've reached 135 mph before I had to get on the binders for the first turn. If you get a good engine, it should pull all the way to redline.
I've not had a bit of trouble with the 99 and power doesn't seem to be a problem. Most S4s I can run from, and the KB
suspension mods combined with the horse power keep me in the pack with most M3s and C5 Corvettes. I think there's not much difference. Just get one with a good engine. And, you probably know better than I how to do that.