how do you make the car louder?

 

Stuff your mother-in-law into the rear seat....

 

Mine has no mufflers whatsoever back from the cat converters.

I appreciate that in some US states it may not pass strict emissions and/or noise specs.

As mine runs on propane emissions are almost zero, and under our MOT rules it may be a fail on noise, however it rely's on them having a stock one in the inspection place at the same time I take mine...which has never happened in 13yrs