I went from having to open the throttle wide open to get it to move in some situations to just having to crack it open just a bit. It is cooler with the True Duals, better sound and much more power. I waited till the HD dealer had a sale, and since I knew the prices, when things got close I jumped on it. so, only $2100.00 installed and out the door, the ThunderMax is normally @$899.99 before discounts. So, pipes, mufflers, stage one kit and install all for $2100.00 well worth it, since it will remap itself as required over the long haul and in the end be more cost effective than a piece here, then remap, piece there, then remap... etc.
As I said if you got the $$ it is well worth it, it feels like a hole new bike.