as this thread is very similar to another thread I am going to copy and paste my post from there into this one, hope no one minds.
Magnaflow does make a very great product on our trucks, and as far as the 4th gen hemis go it is 2.5" in from headers/exhaust manifold to the Ypipe, and then 3" from the y pipe to the muffler, and then 2.5" duals from the mufflers to the tips.
check out the available magnaflow muffler we cary in stock here lowest prices around
Magnaflow 14" Muffler $134.61
Magnaflow 18" Muffler $155.99
Magnaflow 22" Muffler $124.01
These are shipped prices to the lower 48 states.
Discount Auto Performance