I just installed Tri-Y's, dual exhaust and GT trumpets on my 66 a couple months ago. I found a good muffler shop that did all the welding, cutting and bending. I installed the headers. All went pretty well, until last week when the slat piece fell out of one of the trumpets! Running the car with one trumpet open and one with slats, I could definitely hear that those slats add restriction, sort of a "wheezing" through the slats. I'm now going to remove the trumpets and have some simple bevelled tips installed through the valence.
Good luck, you'll enjoy what the dual exhaust does for your Stang!
DanM
66 Coupe, check her out at
http://www.66CoupeNW.stangnet.com
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