I second that Little Boy, I have the T-4 systems on all three of mine. If you you want to see pics on a Prairie/ Twin Peaks, I have some in my pics none are close ups but you can see the pipe some of them. I think the T-4 is the best sounding that I have herd. If you like really really loud I would say the HMF race series maybe more what you are looking for. The T-4s are louder than stock but more of a nice deep rumble that sounds nice and not anoing like some of the really load pipes can be. I have never herd the new QS1 series HMFs, those might sound pretty good but I don't know.

I am curiuse as to how a slip on would work on the Prairies since, correct me if I wrong but I thought I remembered the head pipes being welded to the factory muffler, at least one of the head pipes were, I am thinking it was the rear cylinder that was the one attached.

 

all pipes for prairies are at least "half systems". You are correct the rear header is attatched to the silencer. "Full Systems" include a new front header also.

 

My HMF Penland full system definately made my 650 a lot more snappy. Sounds great too. The quiet core makes it close to stock volume if noise is a concearn.