A 200hp RV7 will climb more than twice as fast as a C182
Failing that, MX2, Yak-52 and all these 2 seat aerobatic aircraft.
There must also be some some 4-seater business jets? Wikipedia says the Lear 23/24 seats 6 passengers? I find that difficult to believe. If you take 4 seats out, then that will be a pretty rapid 4-seat GA aircraft
