It is definately better than stock, side by side I consistenly pulled a stock piped sled by about a sled length, sometimes stretched it to 2 by the end of the hill. We were lined up in about 2ft of powder with a good base. Both 154X's. One was bone stock with some clutching and gearing(Real strong for stock) Oh it had a MBRP can on it. I ran a 154X with a CPI pipe and Glasspacks. Ran a little more weight in the primary, other than that, we were dialed in identical. Swapped sleds several times and the results were always the same. I sold a dozen or so to customers through the shop.
As far as the welding and customer service, I had a buddy who had a CPI pipe and can on his King and the welds split and melted his plastics. Mike was on top of it and made sure the can was replaced as well as the plastics, rivets, etc etc.
I couldn't tel lyou if the pipe made the claimed 11hp but it was noticeable.
Add a Terra Alps head and I think you'd be further ahead. Add all three and it's a strong strong combo.
Plus it's lighter than stock. That's more of a reason to buy a pipe and can than HP gains in my opinion. As long as it doesn't loose HP, it's not obnoxiously loud, and it's lightweight.....that's all I ask. If it's a noticeable difference on the hill.....well that's what matters.