I agree with George, but if he insists on a tube sight, you can get a Carver mount for the Aimpoint. You need to do some surgery to a holster to make it work however.
For the CR Speed, you'll need to Dremel the snot out of it so the Carver mount will fit.
I doubt a comp will do much with factory ammo unless you buy very expensive 135 grain ammo, so you might try it without the comp - or just get some ports cut into the factory barrel. There's another thread on this topic, but IMO you really don't need an aftermarket barrel if the factory barrel produces good accuracy.
Taylor mag extentions have the best capacity. Arredondo are good as well, but only hold 19 or so.