Hello, because the mods, I have made in my engine recently (Twin 40 DCOM carbs, newman phase 1 cam with mechanics,slightly head work) I want to change the standard exhaust for a one less restrictive. My CVH is carburetted version, and the manifold and system are crap. I have changed the manifold for a MFI one, and adapted to my exhaust.
Standard tubing in my exhaust is 45 mm, and at the silencers reduces to 40mm !

I want to make a full line from the manifold made of stainless, with two silencers, as standard, but with more diameter of the tubing. The guy that makes the exhaust can made my exhaust up to 55 mm tubing, but he recomends me 50mm because he think 55mm is too big for a 1.6 and the engine may lost low torque. Also the silencers will be same diameter that tubing, so the complete line won`t have reducers.

What do you think will be better? 50mm (2inch) is enough or will be better 55mm (2 1/4 inch).