I just brought home a '14 WR450F. Haven't even been able to ride it yet because of a cold snap here. Anyway, I see that Yamaha has a "performance" replacement muffler tip in their performance catalogue. I also noticed that they feature a GYTR FMF pipe there too. My question is: other than weight, would there be any noticeable performance difference between the stock mod. and the FMF replacement? I don't want to be too loud but I wouldn't mind "uncorking" the thing a little bit. I will buy the race ECU probably next week, if, in fact it is necessary, and my buddy at the shop says he'll tune if for me free with the Yamaha tuner if I need it. On a side not, I heard/read somewhere that with the pipe mod. (or was it the GYTR FMF slip-on?) you can simply put the race ECU in with the provided map and get very good results. Does anyone share that opinion or perhaps believe otherwise? In the end, I want the bike to run closer to it's design limits, not too close though, and I want to be able to hear it more. I'd rather NOT spend the $300.00 for a slip-on as this isn't the only bike in the stable and these things are chewing through my pocket book and future enough as it is! I ride with ear plugs in most of the time and I'm kinda deaf anyway so it helps me keep it in the sweet spot if I can hear it. As a reference; my last "dirt bike" was an '11 RMZ 450. I don't expect nor do I want my WR to run like that top fuel dragster of a bike but I want to make sure I'm not disappointed either. Thanks guys!!