All:
Not to hijack the thread with another potential option, but I called Borla tech this afternoon and was informed they make a kit specifically for GM Performance Parts, 3" and 3.5" systems WITH a flapper valve, which eliminates ALL resonance. It's a single source agreement where the only option you have is to buy it from a GM dealer. The Borla rep went on to say that GM actually has the 'flapper' fabricated by someone else and they personally assemble the exhaust 'kit' for distribution to dealers. This entire thing was so far fetched to me that I actually called a second time, got another tech and the exact same answer. Finally, this "GM kit" is dual outlet, right side just like the regular Unit, but does not come with any tips, they must be ordered separately, and through GM (probably because they want the bowtie on the tip instead of "Borla." Unfortunately, I've been on GMPP's website and there isn't even a listing for any performance parts for a Tahoe. There is a listing for both a 3 and 3.5" for a Sliverado (5.3 and 6.2) respectively (see link below), but I see no evidence of a flapper valve. Can anyone verify this as true, and if so (and more importantly), provide the GM part number? Finally, in looking at photos of the factory flapper, it looks hugely restrictive. With the understanding that any catback kit is going to produce marginal performance gains, I'd wonder if the flapper might eliminate ANY power gain at all. I guess the big thing is whether or not the 'regular' Borla kit has resonance without the flapper. If the answer is no, I'll just get the 'regular' Borla kit. If it does resonate, this mystery GMPP kit might be work exploring. Thoughts appreciated.
Brian A.
2015 PPV
Silver Ice Metallic
http://www.chevrolet.com/performance/silverado-parts.html
