hopelessbrand

I had a 4" MBRP exhaust on my truck then decided to straight pipe it. I personally like the sound of the turbo, gives it a mini diesel sound!
But my question, for HP\TQ is it better to have a muffler installed or does it even matter?
Just going from past turbo experiences typically faster you can get the air out without restriction the better, does this still play a factor?

asphaltcowboy3

I installed Gibson 4" on my eb and it flows great and has a mellow sound. Was told to have some back pressure but not as much as factory

Aboostedf150

The problem with a 4 inch exhaust is that it allows the Exhaust flow to slow down so much that you loose lots of low end torque and hp..You will gain power over a stock exhaust on top thats for sure. But if you compare it to the best 3 inch exhaust you will see that you will lose as much as 30 hp/TQ down low,and gain little if any in the mid range,only gaining some on the top end..Over all AVG power will be lost which is the most important factor when trying to increase power out put...
Its not so much about needing back pressure either, each size exhaust has its owned about of back pressure,so depending on how you look at it, you either gain or lose a certain amount of back pressure as well depending on the size of the pipe..
As a rule back pressure does not help increase HP.
Each motor must be matched to the correct size exhaust allowing for the best speed of the exhaust gases to gain TQ and HP, no matter what the size increase of the pipe is you will always gain Hp over a stock exhaust.
Even with a lose of exhaust speed once you get to the higher RPM range the exhaust flow,and speed will catch up,and then HP will take over gaining on the top end.....