What is the difference between HFC and test pipe?

efuseakay

I have ERZ HFCs on my G37 sedan. Love them. They were raspy with the stock exhaust, but once I installed my Fast Intentions system, the rasp totally disappeared.

There really isn't much difference between test pipes. They really are just straight pipes. Compare the materials used though. Some use better stainless steel.

As far as performance, there won't be any difference regardless of brands. I would consider resonated test pipes, to cut down on the rasp. Adding a resonator in no way effects performance, other than sound.