You can do a search on it, but here is a quick synopsis: The cam was changed for model year 2000, so a '99 and earlier have the "lumpy" cam. One of the reasons they supposedly went to a more mild cam was to avoid "NGR", or Neutral Gear Rattle. I am told that many, many Vipers experience this to varying degrees, which is just a rattle of the gear/gear shift due to the loping idle of that cam. Because of the nature of the cam (and I am no mechanic), it offers a much better response to bolt-ons, mainly headers. Where a '99 might see 35+ rwhp from good headers, a '00 may only see 5-10 rwhp.
One other important thing to note: The 2000+ Vipers (including the SRT) have hypereutectic cast pistons instead of forged. While the factory claims they are 38% or so stronger than the forged pistons of the '99 and earlier cars, most agree that they should not be used for extensive power adders such as nitrous or supercharging.
Here is an interesting article about the strength of forged vs. hypereutectic cast pistons.
As far as being faster or slower, most of the Gen II's are pretty comparable out of the box. There are supposedly some '97's that run exceptionally strong, while you will also find a very few cars that just don't have the oomph from similar years. I know that my '00 (mild cam) could beat most of the '96-'99 Vipers running stock for stock (tubes and filters anyway). At our dyno days events, we have seen a couple 2000's with much better horsepower than the other Gen II's present with siimilar mods. Once you add headers, the earlier Gen II's will usually take the gold.
Hope this helps to answer some of your questions!
Chris
