Hey!, Fellow Outlaw owner,
My '07 (on a W24) does not have any heat barrier around the mufflers...maybe an improvement in the '08(?) But, my mufflers are not near anything that is heat sensitive...maybe the '08 has the muffler tucked up tighter to the RV floor(?)
I recommend replacing any heat barrier that a vehicle came with.
And, maybe this question could be made in the Workhorse Chassis forum vs. the General Class A Discussion forum to get more expert exposure: Workhorse and Chevrolet Chassis Motorhome Forum - iRV2 Forums
And, if interested, there's an Outlaw Mods and Easy Fixes thread I started:
OUTLAW Mods and Easy Fixes
where details of your exhaust project would be a welcome addition.
Kim and Steve, Mustang LCDR (Ret), '07 Damon Outlaw #1193
I have seen gross intolerance shown in support of tolerance, Samuel Coleridge
WE LOVE OUR OUTLAW RV