Peak figures:
Before: 216whp, 145lb/ft
After: 241whp, 157lb/ft
25whp gain and 12/ft which is fantastic. Essex Autosport did the mapping and were also surprised at the gains. Seems Jim’s new 4-1 design is worth every penny!
now with dyno:
Wow! That is a great increase!
Hmmm where’s Jim’s number 
Damn, might have to upgrade to the new version!
Just the manifold alone will bolt up to one of Jims SDCP?
Neil.
Big improvement - Did yoi have 2bular on before?
What size are the primaries on Jims new 4-1 manifold?
no idea on the primaries. Give Jim a call as I’m sure he’ll tell you the difference between your current and mine. He did smooth out the pipe ends alot from his previous design.
Impressive 
No probs…I was just curious if he’s increase the bore size, or it a complete redesign. Mines already a one off (I think) with 4-1 manifold with 2" primaries into 3" system, but this is probably the old design now.
[quote=C8UER]Wow! That is a great increase!
Hmmm where’s Jim’s number [/quote]
Don,t you dare disturb him … He,s welding mine up !!!
Great results tho …up. 12%
BRING IT ON 
Not bad at all.
So to be quite clear, this is a Redesign of the one I fitted about a year or so ago?
If so now I need to upgrade mine, how annoying.
This is a redesign and from what Jim said on the phone its likely to produce very good results.
I thought it was a good gain when I made an extra 18hp and 20lb/ft when we added to the one i have to my setup, but that gain is stagering, it must fel amazing (if you could get the power down in this weather 
Any chance of some nice piccies please!
BTW, have you had to fit a MIL light suppressor with your decat? If so, what did you use?
I sense Pete,s planning an upgrade !!!
[quote=aelord]Not bad at all.
So to be quite clear, this is a Redesign of the one I fitted about a year or so ago?
If so now I need to upgrade mine, how annoying. [/quote]
The std header/manifold is a piece of junk, barely fit for the n/a motor. For an SC install, it’s a serious block on power. When I first had an Exige S on the dyno, it showed 204bhp. I was first to design a header/manifold that would improve the exhaust flow out of the head. 12-15% gains were achieved. With various mods - re-flashes, smaller pulleys, intercoolers, etc etc the power outputs have been climbing steadily.
So, it was time to have another look at the 4-1.
Steve’s install was a good opportunity - same car, same dyno, same day, same operator. Most of the variables removed. I was interested in the CHANGE because that would have been down solely to the header/manifold.
Worked very well, very pleased.
[quote=321freeflow][quote=aelord]Not bad at all.
So to be quite clear, this is a Redesign of the one I fitted about a year or so ago?
If so now I need to upgrade mine, how annoying. [/quote]
The std header/manifold is a piece of junk, barely fit for the n/a motor. For an SC install, it’s a serious block on power. When I first had an Exige S on the dyno, it showed 204bhp. I was first to design a header/manifold that would improve the exhaust flow out of the head. 12-15% gains were achieved. With various mods - re-flashes, smaller pulleys, intercoolers, etc etc the power outputs have been climbing steadily.
So, it was time to have another look at the 4-1.
Steve’s install was a good opportunity - same car, same dyno, same day, same operator. Most of the variables removed. I was interested in the CHANGE because that would have been down solely to the header/manifold.
Worked very well, very pleased.
[/quote]
Bulk buy (I am in)
Q.
Having spoken to Jim, I think one of these is going to be on the shopping list for the New Year
Oh Exiges…how you cost me money
Them results are petty stunning for a Katana which has no intercooler.
Adding a much smaller pulley and charge cooler seems to be only good for another 30bhp! Defiantly getting mine mapped to 330bhp with a smaller pulley in the the new year lol!
[quote=blacktoy]piccies of it fitted will be on the way tomorrow. In the meantime:
[/quote]
Pic of my 2bular (2" primaries) to comapre…
[quote=321freeflow][quote=aelord]Not bad at all.
So to be quite clear, this is a Redesign of the one I fitted about a year or so ago?
If so now I need to upgrade mine, how annoying. [/quote]
The std header/manifold is a piece of junk, barely fit for the n/a motor. For an SC install, it’s a serious block on power. When I first had an Exige S on the dyno, it showed 204bhp. I was first to design a header/manifold that would improve the exhaust flow out of the head. 12-15% gains were achieved. With various mods - re-flashes, smaller pulleys, intercoolers, etc etc the power outputs have been climbing steadily.
So, it was time to have another look at the 4-1.
Steve’s install was a good opportunity - same car, same dyno, same day, same operator. Most of the variables removed. I was interested in the CHANGE because that would have been down solely to the header/manifold.
Worked very well, very pleased.
[/quote]
Hi Jim. I’d be interested to know how much difference you think there is between your original 4-1 (as fitted to my car) and the redesigned new one - I need to work out the cost-benefit calculation!
I agree the OEM one is crap. Big improvement when I stuck your manifiold on.