I have a ls6 cam in my a4 2000 t/a and I like it. Runs just like stock even with no tune. On the 1st start up right after install it idled rough for like 30 secs or so and after that it has sounded like stock since. Drives perfect and has a decent pick up in the upper rpms. Have not noticed any loss of mpg (I dont drive it easy so kind of a moot point lol) either like I did with my big cammed z06.

On the other hand I drove someones stock manifold and headed 99 m6 t/a witha cam in it and it was a freaking dog. Drivability wasnt terrible like an untuned cammed car but there was like no power down low.

To sum it up:
If you are going to do the cam you have you should get LTs. If you dont want to get LTs then you would be better served with a cam designed to work with a restrictive exhaust side (more duration/lift on exhaust side).
As cheap as LTs are these days no reason not to pick up a cheap set and put them on when you do the cam.

 

If your on a budget then yeah go with the ls6 cam. Plus if your running a a4 you dont need to buy a converter. But if your looking for some power go g5x4. I had a g5x4 with a yank ss4000 built a4 243 heads that had some porting done to them and pacesetters Lt's and I raped a lot of cars (charged cobras and turbo subrau's mainly){NOT saying nothing on these cars. Just wanted to clarify that it performs on paper and on the road}. Oh yeah almost forgot it was untuned