help please

iv just bought a kr engine, i know theres two different 1s, 1 with a cat that has 126bhp and the older 1 that has 136bhp, now i can only see to things different the cat and the air box is smaller, does any1 no why else it has less bhp or is that it cheers

i dont know much about those engines tbh, but from what u have said
the one with less power has a smaller airbox and cat
the one with more power has bigger airbox and no cat ( i presume)

that said, surely the airbox is restricting the airflow into the engine and the cat is restricting the exhaust gases out, thus restricting the power?

just a thought tho

yer what he said and also the earlyer 1 has a larger intake manifold and has a more harsher mapped ignition ecu

there we go then, sorted!!

cheers guys

harsher mapping FTW!!!!