I've just picked up a 2009 DR-Z 400E. It's got a Powercore 4 tailpipe and I'm looking at getting a matching Powerbomb headpipe but I'm not sure if it'll need more fuel than the bike is pushing? Does the 2009 400E need a rejet with a full exhaust system or is it pushing enough? I think it's 165 main stock which should be plenty but I'm no expert. Thanks for your help!