Get rid on the ABS/TRAC garbage and cut a hole out of the inner fender and outer fender (maybe a little more metal work to make it look not half-assed). You could use a compact/slim muffler, say from burns, to help with the noise some but its still going to sound like a raped ape.

(picture for reference)


Might have to do something with the wiring in the area but thats easy to sort...