How much of a difference would it make to power/performance if you had a 3" exhaust, but with a small 2.5" section at the flange on the downpipe? Would it hinder performance, and not make one bit of difference?

And if you got it mapped like this, would changing it to a full 3" system at a later date make any difference to the map? I.e. Should I get a map tweak?

Also, the centre pipe has a resonated section in. If this was removed at a later date, would this effect the map too?



Cheers

 

What HP would you run? If it's nothing seriously high, you would be fine with 2,5" which is IMO even better than 3" - more torque at low rpm.

You can put deresonated center pipe without a map tweak.

 

But you are still limiting by 2.5" center pipe and backbox pipework.
If you looking at higher BHP in near future,you will need 3",i've similar on mine few months back and i end with HKS 3" all way through.


Jura

 

https://www.scoobynet.com/866506-tra...-system-2.html - Page 2:

Why is this a shame?
You will find that 2.5" exhausts or those referred to as 2.5" exhausts are good to well over 400 bhp.
3" exhausts or those referred to as 3" exhausts are generally 2.75" in reality and they are good to well over 600 bhp and probably even more. You need a free flowing box and a relatively straight exhaust system but the actual diameter is not a problem.

Thanks
Sam

 

My centre pipe and backbox is a true 3" internal diameter.

My downpipe is 3" ID, but the last 50mm it goes to a 2.5".

I've got a 2.1 with lots of head work, and a MD321T.

I didn't know weather it would be worth while chopping the 2.5 section our and putting a 3" section in to make it a true 3" system?

I imagine I will get a minimum of 450bhp, hopefully more.

 

I'm not sure,but i've went for 3" on mine build(2.1 stroker with SC50) because i've something before same like this 3" DP tapered to 2.5",but with 2.5" pipework(center pipe and backbox)

3" will be wise in future.


Jura

 

Well I am going to chop the 2.5" piece out, and weld in a 3" piece with new flange.

Although, I am not going to be able to do this before the map! Will changing the 2.5" to a 3" affect the map, or won't it make the slightest bit of difference?


Thanks