Design of these components separates the men from the boys, premier league from 2nd division, the experts from the plagiarists.

My comments here are strictly related to the installs on the Lotus Elise/Exige.

I spend a great deal of time refining the two important parameters – BORE and LENGTH. Doesn’t matter if it’s an N/A or an S/C install, these have to be correct if you’re to access every bhp/ft-lb.

I see claims of having used “software” or God help us, a flow-bench to develop a header. Pray tell me how a flow-bench replicates the exhaust pulse or the returning wave?
It took a lot of R&D to sort the 4-2-1 header for the N/A 2zz-ge. The primaries required a stepped design which means no loss of torque on what is a bit of a gutless motor. On a 4-2-1, the secondary lengths have a direct correlation to the primary – the dyno will tell you.

My 4-2-1 for the 1zz-fe motor fills in the 12ft/lb dip in torque resulting from the factory short 4-1 layout. I see some advocating a 4-2-1 design for the S/C – but even Lotus get this right; they use a 4-1 design as std – they remove the splitter plate from the Cat pipe used on the N/A motor to achieve this.

I smile when I read some klutz claiming his header for the S/C has a 1.875”dia primary “because that’s what Mother Nature intended!” – er, no – it’s what I found works best on the dyno – the real arbiter of header design.
Once the two important parameters have been finalised, I then look to pare away weight where possible, without endangering reliability. This means the 2bular 4-1/De-Cat combo for the S/C 2zz-ge is the lightest on the market – by some margin!
On a recent UK dyno shoot-out for Lotus S/C 2zz-ge, cars equipped with 2bular exhausts were way ahead on power/torque compared to other installs.

Now, fitting a larger-bore header will increase gas-flow but to access the real improvements in power/torque you must match the fuelling requirements – too lean a condition means less power and a danger of melted pistons.  UK owners contact essexautosports.com  for advice on ECU tuning. Charlie Wallace at gotham.am is THE man when it comes to ECU work.

R&D is never-ending – it keeps 2bular ahead of the pack. Some owners are heading for +300bhp on the S/C. I have two larger-bore 4-1 header/system designs for these installs – a 70mm up to 400bhp and a 76mm over that power output. You need to achieve an inlet pressure of  +9psi to make it worthwhile fitting one of these.  The std MP62 supercharger needs to be over-driven to achieve this and the piston rings probably won’t last long at that pressure - +300bhp is a serious power hike – requiring serious hardware.