Induction tuning comes with several considerations:

Length of the induction pipe - this is measured from the back of the inlet valve to the point at which the overall itake assembly reaches open air.

Cam timing - indicates the pulse duration (used to tune length)
Exhaust Port Size - The size of the hole in the Cylinder Head and it's matching to the Inlet manifold, throttle butterfly etc. Ie. ensure enough air can "get in" to the cylinder.

Expected Engine Operating Speed - This is important when looking at high power manifolds, as it dictates intake air speed... it indicates the location of the injector in the inlet tract.

Cold Air Source - Where do you get Oxygen from

High Pressure Zone - where is the air the mose dence.

Raceline/Jenvey (I will consider SBD's onwn seperately) - These offer derect to head mounding and copy the format of DCOE's. They have post Butterfly injector position which will give good mix duration for all but very (very) high engine speeds. They are also single injector housings (which back up again the usual rpm range usage). The rules for butterfly sizings again match up to DCOE recommendations so you can google DCOE recommendations to get a good steer for sizings.

SBD - SBD use individual Throttle bodies which have been selected for air flow matching to the Duratec. They have then tuned the length and shape of the manifold seperately to get best torque whilst maintaining max power output. I'm sure I have seen a multi injector rail version of this on a Westfield which allows for Bank one of the injectors to run in the stock position giving regular running and then a second bank placed towards the intake end of the runners (possisbly even pre butterfly) to cut in at High RPM and probably WOT thereby giving enough time for the fuel air to mix correctly.

Barrel Throttles - Do the same as the SBD TB's but instead of using a Butterfly use a rolling barrel. You will still need to get a suitable inlet manifold to mate these to the Head and air-horns etc. So similar to SBD but minus manifolds.

Cosworth D-Power Plenum - This is slightly different from the above in that it includes an Air Box (which can be put onto all of the above) with a single much larger throttle butterfly and it's likely that it is pulse tuned. By dictating the length from the valve and knowing the likely cams used etc. Firstly it will reflect the individual Intake pulses back into the individual intake tract,.... hopefully making the pulse reach the back of the valve just as it re-opens.. which means that you get a slight "charge" effect therefore a "bit" extra power. You can also scavenge from other cylinders, ensure a generally dense air situation inside the plenum etc. etc. The single throttle is ok but will not let you tune individual intakes to balance cylinders. You will also get more torque as you have effectively enlarged the intake tract all the way to the hose you will need to fit on the front of the single inlet pipe.

Weber also do an "Alpha" injection kit http://www.webcon.co.uk/alpha/AlphaGoldKits.html

If you want an easy application then the Jenvey kit or the Weber Alpha kit are more straight forward.

You will need to think about a closed intake as you have a bonnet and an inner wheelarch which will be Very close (think Cylinder 2 being <10mm from the end of the Jenvey intake (without air horne or air-box).

Pipercross do a slimline airbox which fits under the bonnet with some minor work.http://www.pipercross.net/competition/products_600_airbox.asp
Alternatively there are Carbon versions from Riviere which are more expensive (a lot) and will need more creativity that I've mustered to get to fit!

http://www.reverie.ltd.uk/

I hope this helps somewhat... alternatively you need to read this book:

4 Stroke Performance Engine Tnuing - A Graham Bell

http://www.amazon.co.uk/gp/product/18442...7C0TWAMDJJE3DMK

Good Luck

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