Exhaust size and mpg

let me ask you all this, those who know : what are pro's and con's of going with the one inch bigger exhaust from the turbo? I have the 2006 isx and after the Vgt there is the reducer to the smaller exhaust, vs the Vgt exhaust size. My pipe is beginning to rust through so, I was thinking about changing the pipe from the Vgt to the same size as the Vgt exhaust port, diameter wise. Should I do it or not? Why? Why not? Thank you.

 

It will probably pay for itself in a million miles or so.

 

Explain your answer

 

If you need to replace the pipe anyway then yes go with the bigger one. It can't hurt mpg, but I dont see it being any measurable gain either ...

 

Consider the cost of chrome pipes and you don't gain that much mileage. Can't see buying them unless you want them for looks but that's like putting lipstick on a pig. She's still a pig.

 

Sir, I'm not going to try to insult your intelligence. However, why would I use chrome pipe at the vgt?

 

What about the back pressure and possibility of the Vgt "run-away?"

 

On my o6 ih 9400 its the other way around. The pipe on the turbo is smaller then expands to a 5 inch pipe

 

I diesels gotta breathe the bigger the exhaust the better. But I'm sure I'm stupid and have no clue what I'm talking about according to somebody.

 

i could have swore that I've seen the reducer from the vat. I'll check it again tomorrow.