i have a 06, HHR,LT, with 2.4, engine. purchased a PROTUNE LAB, header, has a single 2/1/2", collector , has anyone put this on their hhr, did U hook it up as duals?, or a single exhaust, or dummy on 1 side ???.

 

Some have tee'd the single pipe out to each side just before the rear tire, fumes can still drift into the cabin with the rear door windows down so consider that deadly problem, others have split the pipe and y'd to dual mufflers. Key dual exhaust in the search window, some threads still have pictures

And welcome to the site!

 

I think it's the 2 1/2" part he's wondering about. IIRC, the standard size is 2 1/8 or 2 1/4?

 

There was at least one early on that made their lake pipes functional.