4-1 or 4-2-1

[Ph1 Tom]

Not too fussed about ease of changing the cat etc as I'll just get a sports cat but what I want to know is...

Is it worth fitting the 4-2-1 for power/torque gains?

With either the 4-1 or 4-2-1 I will fit a sports cat so which is best; the 4-1 with a sports cat or the 4-2-1 with a sports cat?

 

[Fred@BTM]

real world not really worth the effort

 

[Ph1 Tom]

Just run the sports cat and order the Yozza stealth then?

I've got the twin barrel cat on my Ph1

BTW you confirmed on the phone that the stealth was 2.5" but is that 2.5" all the way through including the boxes and tailpipe?

 

[Fred@BTM]

the race stealth yes, the quiet stealth no, otherwise it would be as loud as hell!

 

[Ph1 Tom]

What is the bore through the entire system then? Where does it change?

 

[Fred@BTM]

all our systems have a 2.5inch centre section (the same centre section for all 3)

all the race systems (stealth and normal) are 2.5inch

the stealth quiet is 2.5 inlet into the rear box then splits into a tri chamber baffle and exists through a 2inch tail pipe


the rear boxes are all interchangeable

 

[Dan@SJM]

Fred, how much is a stealth rear box?

 

[105e]

Think general conventional wisdom used to be 4 into 1 for top end power and 4 2 1 for mid range torque

 

[Ph1 Tom]

Yes, although for the rpm range most road cars work at I doubt the 4-2-1 will restrict top end but it will help mid range. That's why I'm tempted to change but are the gains worth it. Renault obviously thought it was worthwhile having spawned the 182 but how much of that is down to the manifold and how much on the sports cat