a good tune with the mods you have you should be around 15-20 hp increase. Which inturn is a .1-.2 decrease in your 1/4 mile e/t. My tune on a stock motor with only a lid, bellow, k&n, SLP cold air and SLP loudmouth gave me 10 RWHP and that was on a humid day down here in Florida. Make sure if you do tune to go to a reputable shop that will dynotune it so that way you know what your car is able to do. I was running 13.0 consistantly with my mods until one low humidity night i finally got her into the 12's. So just get some radials and if the track is real sticky try loading the stall some maybe to like 1000 RPM's or so, cant go to to high with the stocker. Also i felt my gears made the biggest difference so you might want to invest in some. 3.73 is the way to go with the A4. Have fun and good luck.
1984 Cutlass- Project car- Planned LSX with big turbo running E85 backed by a 4L80E and 9 inch rear.
2007 Subaru WRX TR 5spd- daily driver
*SOLD* 2002 WS6 Arctic White A4
*SOLD* 2000 T/A 6spd
*SOLD* 1999 Formula A4