Two Catalytic Converters

I have a 99 Expo with a K&N air intake system, and a flowmaster dual exhaust with a flowmaster 40 series muffler. Man this baby sounds good but I want it just a little bit lowder. Took it to my man and he said it has two catalytic converters and he did not want to put high flow cats on it until my warranty is over. Anyone got suggestions.

Depending on how loud you would like it you can do this, Get rid of the mufflers! I did this on my 2001 Ford F150. I had true dual exhaust, since I cut the Y-Pipe out. It was awsome, sounded like a Nascar truck when you really get on it. Now everyone around me is doing it! Otherwise look for a different muffler!