What type of exhaust does your 273 have??? show some photos!!!
I run the factory style Commando/Charger exhaust on all my 273's from mild to wild, factory exhaust manifolds and all. Combinations ran from stock Commando, to 284 duration solid cam with an Offy intake and Holley carb, to "72" 340 heads and cam with a 71 340 intake and TQ. I am also contemplating using a 67 Charger exhaust for the "73" Dart 318 with a mild hop up. The Y pipe exits with a 2 1/2 pipe to a straight thru muffler using a factory 2 1/4 hanger and a 2 1/4 tail pipe into a straight thru resonator. Been running this combination since the early 70's when they were available from many sources. I tried duals with turbo mufflers and saw little to no gain. Straight thru stainless mufflers can be had close to original length and diameters without spending a fortune.
I run the factory style Commando/Charger exhaust on all my 273's from mild to wild, factory exhaust manifolds and all. Combinations ran from stock Commando, to 284 duration solid cam with an Offy intake and Holley carb, to "72" 340 heads and cam with a 71 340 intake and TQ. I am also contemplating using a 67 Charger exhaust for the "73" Dart 318 with a mild hop up. The Y pipe exits with a 2 1/2 pipe to a straight thru muffler using a factory 2 1/4 hanger and a 2 1/4 tail pipe into a straight thru resonator. Been running this combination since the early 70's when they were available from many sources. I tried duals with turbo mufflers and saw little to no gain. Straight thru stainless mufflers can be had close to original length and diameters without spending a fortune.