Yes, the TTIs will fit your 516 heads. I have them on my Chally and am very happy. The fit and finish are of the highest quality. I opted for the thermal barrier,(inside coating), this has a twofold effect. One it helps keep lowerhood temps. down which helps preserve expensive underhood components and their finishes. Two, it helps "build" horsepower by scavenging the exhaust gasses through the system. The flanges are 3/8 thick both at the manifolds and at the collector. Spend the extra 50.00 bucks for an X-pipe system, it will give you an extra 20-25 H.P. !! The TTIs for raised port heads are the ones you DO NOT WANT as they are suitable only for INDYS, Brodix,Brewer, Bulldog, Stage Six ectt. Also to let you know I went with a 1 7/8 into a 3" collector and I am glad I did. My chassis is set up for the curves and sits fairly low, 1/2 inch to 3/4 inch lower. Visually it looks the same which is what I wanted, however the exhaust can be seen by looking underneath at a slight angle. If I had used a 3 1/2 collector I would have surely "srapped" the bottom of them frequently, this would have been unacceptable for me. Just to let you know!