Steve-
We did not go with flanges, using stainless steel clamps instead.
As to the 3.5 inch elbows, they are available through Tognotti's Auto World in Sacramento or SPD exhausts in Rancho Cordova, CA.
The elbows are actually 3.5 inch "U" pipes that are cut as needed.
The stainless clamps and flanges are not cheap - figure about $170 per car for those and about $45 for the "U" pipes and straight pipes.
We will let you know what we think about them I'm sure!
Pat
