2009 Sportster Custom, exhaust mod: Some Questions

Hello, need help. Have a friend the just bought a stock 2009 Sportster Custom. Wants my help. My bike is '92 FXLR, bored/stroked, etc. I have absolutely no experience with the new bikes. He wants to mod his Sportster. Has already put risers & drag bars on it. Now want to mod the exhaust.

I noticed that the crossover is hidden, low, and black, instead of the old crossover, big, chrome, and across the the pushrods. The new crossover seems to be at the slip-ons, and not at the headers, so some questions.

1. Am I correct that the new crossover is at slip-ons, and not at headers, meaning that if you want true duals, then you do NOT have to replace the headers, but only need to replace the slip-ons.

2. Are there any sensors that are in the slip-ons ?

3. Can the slip-on crossover be eliminated, or is there some technology, or something, that requires that you keep the crossover ?

This is just a start. I'll continue to search the forum, but likely I'll need some more info. I don't want to screw up my pal's bike.