Time to change the plugs.

[paullus]

Hi.
I'm going to service my car (S70 2.5T with RICA 235 remap) prior to the annual trek into France. I've been running it with NGK BKR7EIX Iridium plugs for the past 24,000 miles and have always been happy with them. However a thought suddenly struck me, are these plugs the best choice after the remap or should I have gone for a cooler plug?

I have also been looking at the Denso Iridium Power which are a bit dearer than the NGKs but I can't work out which plug I need. Different comparison charts give different answers. It's either the Denso IK20 or IK22.
Any information & help would be appreciated.
Thank you.

[paullus]

I finally went for the Denso Iridium Power IK22 plugs and fitted them yesterday along with a new distributor cap and rotor arm. Immediately I started the engine up I noticed it ran smoother and somehow quieter. It pulls better too so I'm hoping MPG may improve a bit if I don't enjoy myself too much.
Iridium plugs do have an extended life compared to copper plugs of up to 30,000 miles but the NGK Iridiums I replaced were definitely past their best at 24,000 miles.
The cap and rotor aren't changed regularly as part of a service either. However after 35,000 miles both were showing significant signs of wear and carbonisation of the contact areas which reduces the efficiency of the ignition system.
An easy job well worth doing giving a noticeable improvement.

[paullus]

Have had the Denso plugs in for two weeks now and I'm mightily impressed. There is definitely a noticeable power increase over the previous NGK Iridium plugs I had been using before. The engine is smoother and I'm getting slightly better fuel economy too.
Well pleased!