I put together a 2009 Street Glide with the Harley Stage IV. The bike now has 5K miles. Very Streetable. Dyno runs show 110hp/ 106tq- rear wheel output. The only thing the kit is lacking are the automatic decompression valves and harness'. No significant sacrifice to mileage. Ran 13.2 @ 102MPH in the 1/4. I absolutely love the kit (especially when it was purchased on a dealers 20% off day) The bike runs stock up to about 3000rpm then as it comes up on the cam it flutters for an instant then HANG ON. The kit is definitely top end but nothing lost down low. For the money I don't see how this kit could be beat. The shock value of watching a bagger bring the front end 1' off of the ground at 25mph and carrying it is priceless.