It wouldn't be overkill, but it would take a pretty serious engine to take proper advantage of it.

That depends on how much boost you want. Spinning at crank speed it will pump roughly 2.1 times the engine displacement in. The boost pressure will depend on eficiency of the compressor and any intercooling. Intercooling will reduce temp and pressure giving more power for the same pulley ratio. Without intercooling I'd guess at about 18 psi boost. Probably fine with e85. With intercooling it would be closer to maybe 16psi boost and you may get away with PULP fuel with good tuning.

You'd never use it's full range though, you could happily use that charger on a 3-4 L engine.

Take this with a grain of salt as it's a bit of a thumb rule based guess.

I reckon that's definitely on the too big side.

18,000 & 20,000

Probably more suited to 2 - 3 litre motors, but it kinda comes down to how you set it up and what you want from it.

Pricey that one.

Sprintex Superchargers

These guys have an online blower calculator that might help

Do you think this Whipple would be over kill on A15 motor ?? Overall Length:420mm
Width:220mm
Height:135mm
Snout length: 140mm
Displacement: 1.6 Liter/Rev
Max continuous RPM: 18,00
Max Peak RPM : 20,00
Max CFM : 1120
Max PSI : 30psi
Peak VE : 99%
Inlet Dimensions : 120 x 35mm
Outlet Dimensions : 140 x 80mm