[onewhippedpuppy]

So a few things:

As mentioned, the wing is the factory Aerokit part if it looks like that. Very desirable upgrade that really makes the 996 more distinctive. It should also have the more aggressive front bumper, side skirts, and maybe rear bumper mounted flares that were optional. It is the same styling as the 996.1 GT3 that we didn't get. You actually can get a full Aerokit on the 996.2 that is almost identical to a US market GT3, the side skirts are sharper looking and the wing is more of a single plane design.

The 996.1 was 1999-2001, 996.2 was 2002-2004. The biggest change was going 3.4L to 3.6L, the 3.6 is much more torquey but also doesn't like to rev as much. Personally I don't feel the extra 20 HP, but you can tell a big difference in low down torque. The 1999 was the only year with a dual row IMS and a cable throttle body, to me they are the most responsive 996 and are my favorite (I've had multiple of both). The dual row IMS has a much lower failure rate and were not included on the class action lawsuit because of it. Otherwise the 996.2 got a wider track, I think slightly bigger brakes, stiffer chassis, styling changes inside and out, etc. Personally the 1999 is my favorite, it's raw without being rough and a lot of fun. The 996.2 is another step in the GT car direction, it's faster and more capable than the 996.1 but also not as much fun.

I haven't ever had a C4, but also haven't read anything bad about the system. You can quickly pull the front halfshafts if you to disable the system. Some, particularly in the 996TT world, have removed the entire front differential and propshaft to drop weight and make it back into RWD. Supposedly not that hard to do.

Really these are pretty robust cars, both the .1 and .2. They wear well, don't have a lot of little annoying issues, and are easy to work on. IMS is the bad word, but also overhyped by the internet. Of the 5 996s and 3 986s that I've owned, only one had the IMS replaced and it was preventative. Not saying it doesn't happen, but it's not the ticking bomb that some like to represent it as.

Options also make a big difference in value, so pay attention to what it has. Check the sticker on the underside of the front trunk lid for the codes.