whats the diff between hfc and test pipes?

 

HFCs offer environmental protection and test pipes don't.

All test pipes are illegal and HFCs aren't except in strict jurisdictions.

As far as performance, test pipes offer slightly better performance since they're just straight pipes with no honeycomb inside.

 

would there be much sound diff?

 

A little, just make sure you get resonated test pipes. Resonated test pipes will be a little louder than HFCs.

 

thanks