Nothing beats research on the internet for stuff like this!
There are so many thoughts on 'header' design... it's really specific to the application. For our cars, something for most people has to 'work' all the time... without any 'how to drive a car changes'! The Honda Civic 'Type R' was a great example of this... bugger any torque below about 4,000 RPM, and all the power above 6,000 RPM! But if you were minded to drive it as it was designed (for a 'petrolhead'!), it was great fun! Revving the nuts off it with WOT up to 8,500 RMP... and the Honda S 2000 was even better... up to 9,000 RPM!
I noticed a HUGE difference after fitting the LIbrands manifold. Today I had the 'Williams' re-map done... I have now driven about 200 miles with it and have found it hard to tell any real difference, aside from a willingness to rev cleaner up to 6,500 RPM and also generally a smoother power delivery. Which is nice, so it has been worthwhile doing.
Re the comparison to the 'Plus 4' that yes, I did indeed own before 'upgrading' to my 80th Anniversary 4/4! The GDI version which I had, yes it has more power of course, but then it's also quite a bit heavier. So overall, I would struggle to actually feel that difference. But the 4/4 is so much lighter, it's much more fun (IMHO) to drive! Smaller, more responsive, and the Sigma revs very freely... it's such a nice experience!
I would love more power... I think about 160BHP would be perfect. Not too much to then maybe need the 'anti-tramp' bars or leaf springs, but enough to sing and breath more. Caterham have done some great stuff with their Sigma offerings...
Watch this space... I have some irons in some fires! I don't want to go for TB's... a bit to extreme for me as I will not be 'tracking' my car, even though the noise is addictive!
Hope this has been useful!
Cheers, Pete >)
