The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - CA Thorley 399Y-3 Headers, Magnaflow muffler

JEM · 06-10-2011, 11:39 PM

bumpity-bump.

Oh, and after further research looks like the part # for this set is 399Y-1S. Only difference is still the Y-pipe-to-muffler connector.

06-10-2011, 11:39 PM	#4
JEM Ironmonger Join Date: Dec 2004 Location: SF Bay Area, CA Posts: 127	Re: Thorley 399Y-3 Headers, Magnaflow muffler bumpity-bump. Oh, and after further research looks like the part # for this set is 399Y-1S. Only difference is still the Y-pipe-to-muffler connector. Last edited by JEM; 06-11-2011 at 12:35 AM.