I have them. As far as the plastic goes, it really depends on the type of race cut you have...I had to cut mine to get them to work, but I have a buddy who has fullbores and he had to do a little minor sanding.
Performance, they are reallllly great pipes. Hit hard and hold all the way through really, I love them and I've had CPI, T-5, DMC 916...I dont see myself going away from these pipes.
The only problem I have is the "hi temp" paint is garbage, so I'm probably going to end up having mine chromed or PC black with some good stuff.
But yo answer your question, yes that are the shiiiiiiiit!!