I know the powerbong headers worked good on the Ex's, alot people have them. I don't know about using the stock uffler but u could just get the FMF qmuffler, it is designed to be quiet. If ur not happy w/ K&N's then get a Uni, Twin air or WB powerfilter, i have only seen the powerfilters but i havn't looked for Uni and twin air. Where is ur throttle cutting out? 1/8-/14? 1/4-3/4? 3/4-Full? A thiner head gasket might add alittle but not to much.
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