exhausts-by-design.co.uk/default.aspx
come questo su Eliseparts..
eliseparts.com/products/show/39/301/ep-stepped-bore-manifold/
qui c´eè scritto un po di colletori..come devono essere..;-)
kengine.dvapower.com/
Exhaust manifold and system
It is important not to underestimate the affect a properly designed exhaust can have on an engine, the stock manifold that comes with the K series as installed in the Elise is pretty awful, having very short primaries and a lot of welding clag in the inside of the manifold flange, the very least you should do with one of these is to fettle away the weld build up inside the manifold. Some of the Caterham manifolds are also very short on the primaries as are the manifolds which come with the K series as installed in its original Rover home.
Rolling road tests have shown that the best configuration for the 1.6/1.8K series is a 4-2-1 manifold with 30-32 inch primaries of 1.5inch diamter and 10-12 inch secondaries of 1.75 inch diameter culminating in a 2.25 inch system, this setup brings large gains in the low and mid range torque without affecting top end power. Long 4-1 manifolds can give a small improvement at the top end at the expense of torque lower down. One Caterham owner who changed from the short 4-1 standard Caterham manifold to a long 4-2-1 custom made manifold saw an increase of 30ft/lb at one point in the rev range and an increase of 20BHP on the peak power figure, this was on an engine with modifed VVC head, DTH bodies, 835 cams and M3D engine management, the improvement made was solely down to the manifold.
There are a number of people who can supply or manufacture a manifold for your engine, QED make an excellent one for the Elise, Exhausts by Design and Powerspeed have both made excellent manifolds for Elises, Exiges, 340Rs and Caterhams. Given the choice I would always go for stainless steel, even though it is more expensive it is more durable and attractive on the eye.
Shown below is the EBD (exhausts by design) 4-2-1 manifold for the Elise/Exige, it is made in stainless steel and costs £350 It's been proven to work extremely well on the dyno.
As far as the exhaust system goes there are even more possibilites, quite often the standard exhaust systems fitted are quite poor and restrictive, a decent after market straight through absorption only system is a better bet but be wary of noise levels. If you can, buy a system which has a repackable silencer preferably in stainless steel.