Hi guys, just changed the front bank to NGK Iridium plugs, a few things I' liked to ask, How much difference does spark plug leads do?

anyway, the car seems a lot smoother with the new plugs, doesn't sound as noisy.

I'll be changing the rear bank when I have more time next week.

Another question to the people who have changed the intake plenum gasket to some other heat resistive material, just want to know whether you guys used Silicon 1.5mm sheets. that's what the guy at Clark rubber suggested as Silicon are one of the best high temp rubber material they have. I'm also going to see if there can be anything that I can do to the throttle body and plenum to smooth it out more.

You can always get a dremel and smooth out the internals of the plenum runners... Buy lots of the cutting wheels though as you will run out of them quicky even though the plenum is aluminium and quite soft.

If your thinking about doing that then make VERY sure you thoroughly clean the plenum of all metal filings as if they get into the chambers they will wear like almighty hell.

I'm planning to wash the parts with a lot of Carby wash, going to clean the throttle body while i'm at it.

the way i see it the problem would be u wouldnt be able to get right in to the middle of the runners, especially as they have a big bend in the middle. if u had lots of time to play you could....

cut out the major section of the runners and replace with new pipe and port /polish whats left.
cut about 3cm above the base, also cut about 3cm before the main large body of the manifold (connected to the throttle body).
Then you could nicely port and polish the remaining section over the engine and the remaining section after the main intake body. in between make up new pipes from stainless that are a bit larger diameter mandrel bent, an exhaust shop could make them for you.
Cut some material out of the castings between the bores of the runners and fit the new pipes in maybe using some silicone hosing and clamps, BMW M car style.

Well at first I wasn't going to go full out polishing the runners, as you're very right, it's too long. But your idea of making a custom intake plenum is a good idea! I just gotta tune the lengths that's all. WOW, you're a legend!

I think I should get the guys at work to make me a new intake plenum out of mandrel bent pipes and get them to make me a chrome cover for it!!!

I wouldn't start messing with your runners, they are tuned at their optimum as it is and modifying them if anything will only make you loose power etc.

Polish them as you wish, just don't start cutting and welding lol

i think he could sacrifice some bottom end and fuel economy, but gain in midrange and top end power. it would only be worth doing if other breathing mods and dynotune were also done. in any case another 2nd hand manifold wouldnt be much to get if it didnt work well.

I reckon if your gonna cut the runners and make your own, get rid of the single throttle body and go with individual Tbs for each cylinder, you could probably pick up parts off an RB26 or RB30 engine that could be fabricated into the finished product.