What Did You Do To Your HHR Today?
Didn't realize that...figured it had the same exhaust setup as the 2.4 HHR. I'm running a full custom 2.5" exhaust with cat delete (still have cat on downpipe) running through a magnaflow muffler with no resonator. I'm tuned with Trifecta and could feel some difference from the single cat delete and larger pipe. I wouldn't go full catless unless you live in a city that has no emissions or you're tuned.