You didn't mention which model you have, shame shame. If it's a 1330, you will never get a "motorcycle growl" out of a three banger.
Like Mike, I have the stock muffler and a RLS cat delete with expansion chamber and a mild baffle. It produces a smoother, lower tone but only a tad louder.
Talk to Ricky at RLS, he's the designer / builder and he can tell you exactly what sound you will get. This is a good time to spring for his products as he's offering $50 off right now.
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