I think someone has a supercharger but that is all I have heard. Go Summit and Jegs and see if they have anything listed or maybe just bounce around the usual suspects, Hooker, Hedman, Edelbrock, Two Guys, etc. I have an interest in this so I will post anything I find, too.
I ve checked out 20 or 30 web site in cluding those and had no luck. The reason why Im trying to find some that makes a header and or other mods for the LL8 inline 6 engine is if they make anything for the 6 then they'll make something for the inline 5. Ive even contacted a couple of magizines and have gotten no reply and my next step is to check out sema's website.
They will make them. Don't worry. Sometimes the manufacturers don't provide a preproduction mule for the aftermarket. It will just take some time. One point though, the exhaust manifolds on the newer gen V8s are pretty efficient, maybe the Atlas line has efficient manifolds. As far as exhaust is concerned, find a good local shop and up the size and add an aftermarket muffler, cat, etc.
Give it another year or so for the aftermarket to catch up. It will happen.
the upgrade of a muffler be no problem but the high flow cat would be...the cat is located in the manifold itself. ive been talking to borla and dynomax and havent gotten any good news about either the 4.2 l or the 3.5 l. Still looking and hoping.