whats this fasination with cannons.....sheeze...
why not go for either a straight through muffler or a muffler with one baffle....cannons on old cars look shithouse (some are exceptions).
get a nice droopy tip or choose a exhaust tip that you think will suit the car well.....f@$k the fart cannon off altogether...you'll thank me later.
ps. it will sound heaps better too...