Bitchin' cars, I say go for it. The 550 actually feels bigger to me, they really do a good job of masking the size of the 300. The closest factory performance group doing the "M" thing in America is SRT. GM's HPV and Ford's SVT are still struggling to carve out an identity for themselves where SRT has been serious since the Viper, and every car they've touched has been a true factory hot rod.
And I heart my Dodge pickup.