I have KB headers, and they can be removed withthe engine in the truck. NO, it AIN'T easy, but each time you do it it DOES get easier.
If you are bent on doing a retorque, I have 2 suggestions.
1) Kind of half-assed, but just do the retorque on the bolts you can get at without removing the headers. Basically all of the head bolts under the valve cover. If you find ANY of them are not where you initially set them, then yank the exhaust and retorque ALL of them.
2) Probably the correct way here. When you assemble the exhaust, use only a couple of bolts to hang the headers (Obviously the ones that can be easily installed/removed). This approach also goes for mounting the turbo(2 of 4 bolts should work), crossover(1 or 2 bolts in each), and downpipe. This will make your exhaust removal so much quicker, and I can't see it hurting anything as it's not like you're going to be throwing any boost at it for a couple of heat cycles. Then do the retorque, and reinstall the exhaust system will all of the bolts(and threadlocker!).
You're bound to make mistakes when installing KB headers, as there seems to be a certain sequence that must be followed. Most likely you'll tighten a couple of header bolts, only to find out that they need to be left loose until something else is installed. I've had mine off and on, with the engine in the truck, a few times now. It seems to get a little easier each time IMO.
***One more thing I've learned from making the same mistake over and over. Get a few towels and stuff them in between the engine block and the frame on each side, so WHEN (not IF) you DO drop the header bolts, they don't 'disappear into oblivion'. They damn near never reach the ground! :fist: