SP Concepts 2 into 1 Harley Exhaust System Review By: TC Bros. 

Are these systems back purged?

Same. Copies

Just gonna keep it real here.. can’t compare short shots to a 2 into 1 performance system. Short shots are loud and great for looks. 2 into 1 is for performance and getting shit done when you give the ole high ho throttle. Short shots are much louder but these sound much smoother and great

They dont come with them but you can buy them separately from sp concepts

Yes

Hello, Yes, generally speaking an aftermarket complete 2 into 1 exhaust is going to provide better performance than a slip on kit will.

1 to 2 9s always better for scavenging

You mean like all.harley products