theyre smooth and when the charger kicks in on acceleration, they take off like a rocket
they have a blow off valve, so the charger only kicks in under heavy acceleration, which means economy is like a normal ecotec unless you give it a boot
the charger is supposed to last the life of the vehicle, so theres no additional service on that
check engine mounts if u get one tho, i found mine were cracked 1/2 way thru, and the rear tranny mount has a shake in it as well, which i havent got to yet.
besides that you wont be disappointed
i average 15l/100 doing only city driving with constant stop/start, and giving it a boot here and there