Alot of money spent for a gain of 15-18hp and the assurance of replacing the blower alot sooner. The pulley salesman was doing his job. Selling. I would love to see the dyno sheets that show a 26hp gain.
The stock blower on WOT is 7-8psi according to my gauge. The aftermarket pully might get it up to 12-14psi.
For the cost of the parts and subsequent blower replacement it's just not worth it. But hey, it's your truck so good luck.