Which is better 4 or 5 inch Exhaust for the SCT? Is the 5 worth the money?

[local851ff]

I am getting ready to make this purchase and was wondering if the 5 inch was worth the extra cash? I am planning on running an SCT in the future and want to have the optimal exhaust for that. If the difference in performance is negligible I will just stick with the 4. What do you think?

[SamW]

you wont know a difference. 5 in is throatier, 4 inch has more whistle. other then that, there is no difference at all since the turbo provides all the backpressure

[travisH3]

i would just go with the 4 inch, i suggest diamond eye for exhuast. if you go with mbrp know that you will have a 3.5 inch down pipe unless they sell a 4 inch down pipe kit separately so if you got the 5 inch it would go 3.5 down pipe, 4 inch for a little then 5 inch the rest of the way back. diamond eye has a true 4 inch down pipe with there kit. there 5 inch kit has 4 inch dp then 5 inch cause there no way to get anything bigger than 4 inch up to the turbo.

[SPEEDJUNKIES750]

I have the 4" with an SCT and it runs great.

[local851ff]

Thanks for the input on the Down Pipe!!!

[Crmsntide27]

Either one will function just the same. I had a true 4 inch and when I had some work done on it the Ford tech was telling me that the 4" downpipe is a really tight fit up by the turbo and firewall and that over time it could possibly come loose. I dono if he was just BS'n me but I went ahead and swapped it out with a 3.5" downpipe and there was no difference. He said the 3.5" will also provide slightly more back pressure.