Jeep 4.0 in 69 Barracuda
So not to get too geeky here, but the Surface Area of a 2.5 inch exhaust system is 4.9 inches. The Surface Area of a single 1.75 inch exhaust system is 2.4 inches. So a Siamese dual 1.75 inch system would be just a hair off of what a single 2.5 inch exhaust system at 4.8 inches. The presentation of of a Siamese system would absolutely killer, and the main benefit would probably be clearance.