Diameter and torque

[mlivkovich]

I have standard exhaust system on my k2 except cans are modified (42mm outlet). Few days ago I changed it to 4-1 configuration, I put k5 collector. While putting it I could see the diference in collectors outlet pipes diameter, two ends on k2 are each larger diameter than one on k5 collector. While I am waiting for my friend to make custom middle pipe for my beast I put one oem can. Now the sound is more quiet but I have feeling that I lost some torque It pulls hard but the sound is missing (maybe it's just me) or my 14 really can't breathe properly with one k2 can?

[KiwiCol]

What you say Mlivkovich sounds logical. Thinking about the exhaust, the engine needs a certain amount of back pressure to run best, if the K2 gets this from using 2 end cans & you change down to only having 1 available, logic would suggest it's being strangled a bit.

[mlivkovich]

Pipe diameter does not affect the back pressure? So, K5+ bazooka has more flow and creates less back pressure or am I missing it? 

[T 24]

Back pressure or not, but forged the back pressure theory. There are so many things that can make the difference.
Adjust your engine with your new exhaust system and compare after that.