90CSQ woes

[Elliott Potter <epotter@abraxis.com>]

The car:
1993 Audi 90 CSQ
no mods; after I bought this, and send my kids to school, and pay the
bills, etc, I can't afford any...

The story:
I'm sitting at a traffic light on a two lane road; I'm in the left
lane.  On the other side of the intersection the road is straight and
flat for about 1000 feet, then the right lane merges into the left.  I'm
sitting there enjoying the song on my radio, when I feel a slight
vibration.
bam...bam...bambambam...bam...bam...bambambam...
In fact, I can almost hear it.  I look around the car; I'm feeling
around the hood, on the stick, trying to find the source of this.  Now I
can hear it; it's a steady
bam...bam...bambambam...bam...bam...bambambam...
I'm about to get really worried when this HUGE Chevy conversion van
pulls up beside me.  There's some teenager in the front seat with one
hand on the wheel and the other hand wandering around the person in the
other seat (well, that's what it looked like; I couldn't tell from down
there on the ground...)  Also, this van was vibrating in perfect rythm
with the vibration I felt.  Question answered.
The light was red for a long while, and this kid's stereo was really
grating on my nerves, and it was obvious that he was planning on zipping
forward and getting in front of me where the lanes merged, which just
happens to be one of those things that I can't stand.  So, when the
light turns green, I floor it; my Audi leaps forward with a burst of raw
power, and I leave him in the dust.  As the tach reaches for the red
lines, I look smugly in my rearview mirror and see...nothing.  Sure
enough, this huge Chevy van is still right beside me.  We stay neck to
neck until the merge is right upon us; then the kid (smarter than me, I
guess) backs off and gets behind me.

What worries me is that this was no racecar beside me, not even a
minivan. This was one of those 12-foot tall numbers that seats 8 and has
a 2-foot-wide isle in the middle, and a TV, and a refrigerator, etc. 
Compared to an Audi Quattro?  Is there some secret I've been missing? 
I've never seen one of those vans at a race...

Surely there must be some mod that's within my meager budget that will
squeeze just a little more out of my car than that...

Thanks

Elliott
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reply addressed altered to thwart spammers.
epotter@abraxis.com