Personally adding a turbo or supercharge to an XB would be a waste of money becasue your not going to get a whole lot of horsepower anyway. The car is a box, not to much arrow dynamics. When I first got my box I wanted a supercharger but came to these realizations and decided to spend my money on Air suspension so I can cruise low and slow in my box. I guess its just personal preference.
06 Lambo Murcielago: 6.3 lb/hp
06 WRX STI: 11.2 lb/hp
06 Lancer Evo: 11.3 lb/hp
06 Accord v6 coupe: 13.5 lb/hp
06 WRX: 13.9 lb/hp
06 Civic Si: 14.6 lb/hp
06 Chevy Cobalt supercharged: 14.6 lb/hp
06 Nissan Sentra SE-R V: 15.5 lb/hp
My xB (turbo @ 146hp): approx 16.5 lb/hp
06 VW GTI: 16.5 lb/hp
06 Cadillac Escalade: 16.7 lb/hp
06 PT Cruiser GT (turbo): 16.7 lb/hp
06 Mazda 3 S hatch: 17.7 lb/hp
06 Scion tC: 18.2lb/hp
06 Civic coupe: 18.3 lb/hp
06 Saturn Ion Red Line: 18.3 lb/hp
06 Mini Cooper S: 20.8 lb/hp
06 xB: 23.3 lb/hp
I had some extra time on my hands.
I do realize that lb/hp doesn't tell the whole story, you have to take into account the gearing, weight of the driver, etc. and btw, aerodynamics has little effect when going 0-60, I'm not saying it has none, but it doesn't have as much as you emphasize (I can say this thanks to my B.S. in Aeronautical engineering). But anyway, you can see that my box has pretty decent lb/hp compared to other cars, plus with what I've done so far, my car is only $14,000. If you want better acceleration especially when merging onto fast traffic with those very short on ramps or if you want to surprise one of those modified civics, then go for it. It's fun to see the expression on people's faces who think you've got a stock engine.