Pics of the Magnaflow part - i made a post about it last year ago
Idea is that maganflow will flow better than original OEM, maybe because it is new.
People install headers without removign exhaust, you shoudl be okay, follow any e82 or 9x header isntall diy. There is one diy with Superprint headers
All manifolds are pulled from under the car.... not from top.
I hope you find tips on how to get those stubborn bolts.