You can literally double the horsepower of your Honda Civic Si sedan via a bolt-on supercharger kit from Comptech. That’s 400 hp and it seems you don’t really need any major other modifications to run that power.
Matt Farah tried out one such Civic and was very impressed with how it all came together. Aside from the supercharger, the car driven in the TST video posted below has new, stiffer springs and sway bars.
For the blower to be able to give you the necessary boost to push 400 hp, you also need a big aftercooler, though, but that really is all that’s been done to the car.
It sounds pretty good, it still revs like a Honda should and it’s as practical as any Civic sedan. The price for the supercharger alone is $3,300, but it doesn’t sound steep at all considering how much extra go you get.