Also lets face it: the car is a mom-mobile. I absolutely adore ours, and when it's finally time to retire it (and this won't be for a long, long time) it's going to be a sad day indeed, because there's not another vehicle in the road that's anything like it.
The biggest mod I did to ours was soundproofing the interior and adding a nice stereo. Obviously this is the polar opposite of a performance mod, but holy cow, it does make the drive far more comfortable!
Our vans have zero sound insulation in them. Like, none. I went whole hog, ripped apart the whole interior, and triple treated every surface except the roof. (I didn't feel like removing the headliner)
Instantly, just driving down the road, the van felt oh so much more comfortable. No more incessant drone.
So maybe you can do like me and make your "performance" mods comfort mods!