My headers were a little quieter than my SOLO's eveywhere except for WOT. Even the LS shop noticed when they did the initial install. Then when I had them removed, the difference was confirmed. I'm guessing it's the may the difference between the L99 and LS3 or combination of other bolt-ons.
Since you were asking about one brand of HFC versus another. If you ever have an issue with SOLO's you can talk to the owner directly or one of his vendors. The customer service is great.
