Yes a lack of back pressure can cause the oxygen sensors to read improperly, which would turn the check engine light on.
Are you trying to remove the exhaust manifold,the muffler,or just the line running from the manifold connection to the muffler?
im not too sure but i think its because ur kind of pushing it into a smaller space which means that the gas doesnt have enough room therefor having to remove some.
No
Yes
Hacksaw
remove the muffler and add a loudener
No, it is for noise only.
remove muffler
Remove the muffler (don't remove the exhaust pipe or the muffler joint band, just twist the muffler off). Remove the caliper housing. Remove the brake pads. Twist the caliper back into the body (large screwdriver or tire iron twisting to the right and pushing at the same time). Install new pads (making sure that they seat right. Re-Install the caliper housing. Re-Install the muffler.
Remove a muffler.
remove the muffler and add a loudener
the resonator is a separate part of the exhaust system not part of the muffler it is to change the tone of an engine sound some are mounted before the muffler and some after the muffler if you really want to remove it cut it off with a sawsall or chain cutter and weld in a piece of pipe or look at a aftermarket exhaust catalog many replacement pipes omit resonator's.