2.5" vs 3" 2nd De-cat

[mattdavies]

I currently have a 3" 1st decat - RR - 2.5" decat- 3" blitz nur spec setup on from my turbo back and I am BPU

 

I have been wondering if there any advantage to upgrading the 2.5" de-cat to 3" de-cat ? I have had a look on the interwebs and could not turn anything up. What are peoples thoughts or experiences ?

[Lee_e]

It can only be better for the flow so I'd say it would make an improvement, but you would be more prone to boost spike.

[Guest luki77]

i dont know

http://freeflpics.gq/9/o.png

[mellonman]

I would of thought there would be no gain with the way you have it , but if you set it up

 

3" -3" rr 3", there maybe a little gain

 

but im sure even with the setup being

 

3" 2.5" rr 3"

 

you would gain a litte to as the rr causes a massive restriction almost like a wall but staging down to the 2.5 to the ring acts some what like a funnel , as for the 3" 3" it will have more spare to fill before back preasure is an issue

[Nic]

Replacing the 2.5" 2nd decat with 3" will help the exhaust flow better but it will probably also mean an increase in boost pressure, so you'd need to fit a smaller restrictor ring which would likely cancel out any benefit.

[mattdavies]

Replacing the 2.5" 2nd decat with 3" will help the exhaust flow better but it will probably also mean an increase in boost pressure, so you'd need to fit a smaller restrictor ring which would likely cancel out any benefit.

 

Dont think this would be an issue as should be a 1 bar RR, but I see 0.8/0.9 bar.

 

So from what I understand ultimately as I have a RR the upgrade to 3" would be negligible due to the RR acting as a air dam