hi everyone,

Just out of curiosity what are the best plugs and leads to use. im considering getting some 8mm eagles

I have used Champion steel core 8mm and Bosch Motorsport (blue), and have had good results with both. And they both have good warranties. Did manage to pull the boot off one Champion lead, but that would probably not be Champion's fault.

Bosch, NGK, or any other reputable brand should work just fine. I have been using projected tip Autolite 985s as they are supposed to give a coupla extra kws (according to Jim Mock). Could be pure snake oil, but they cost no more than other brands, so nothing lost.

did the 8mm leads seem to make any diffrence power wise?

The short answer is no, I didn't notice any difference. Leads will normally make a difference only when they are in borderline condition in the first place. All else being equal, different leads will both produce a spark - so both will ignite the fuel/air mix. But the harder it has to work, the earlier a borderline lead will fail to spark or spark too weakly to ignite the mix. A bog standard lead will almost certainly work just fine in an unmodified engine. But it may not cope if you run gas, increase the compression, run boost or nitrous, increase the rev limit, lean out the mixture, or anything else that makes the mix harder to ignite.

That's a long-winded way of saying that if your ignition doesn't have issues when pushed now, changing leads is unlikely to make it better. But all leads (and coilpacks and spark plugs) deteriorate over time, so sooner or later it will get to the point where changing leads produces a benefit. And a quality lead will handle a lot more a lot longer than an average one. If you have doubts at all about the condition of your existing leads, it's probably cheap insurance to change them. And they won't become a limiting factor or weak link when you add modifications.

Spark plugs can make a little difference, especially right at the limit. Racers will go so far as to index the spark plugs - shimming them so the side electrode is oriented to reduce interference with combustion and to expose the spark more. In theory, a projected-tip plug should start combustion marginally closer to the centre of the chamber, allowing more complete fuel burn (more power and efficiency) before the exhaust valve opens. Head designers try to get the spark plug as central as possible for just that reason, so there must be something to it. But could you measure it? Who knows.

I run Bosch Motorsport (overkill leads) and NGK's.

These are not high strung motor, standard bosch or eagle leads are fine as are standard plugs. You can go something a bit fancier just to float your boat, hence why I got the motorsport leads, for the sake of maybe $20 or so, I get blue leads that on paper are better, Standard off the shelf NGK's gaped correctly suit the purpose very well. there is better stuff to put cash into than leads and plugs. Invest some in a fluid change on your diff or gearbox. new leads, throw some paint on your rocker cover. share the love round a bit.

I'm running ngk laser iridium's with 10mm top guns on my EF XR6

run any better then stockies?

NGK standard plugs with Champion Steel Leads(Jim Mock uses these on his DEV's kits)

Does the job quite nicely, but now I'm thinking of putting au2 coil pack in along with a few other mods

AUII coild pack is not compatable. you need to put in an AUI pack, same plug set. Just ask ash about how impossible it is to make AUII and III gear work on anything other than AU II or III.