I have a chance to buy us or euro version for the same price... I know that the us version is tamed down by the muffler and pipe (you need to replace both to get the power back) but the dyno charts show that the euro version also has very restrictive exhaust. It seems it has about the same power as other 450 till about 6-7000 rpm then basically stops pulling...2-5 hp less max power than the others. Now...if I get the euro version do I have to change the pipe to (as with us version) or only slip-on will be enough? Anyone ridden both versions or put only a slip-on on euro version?