M3 4.0L V8 Gpower and Evo X Spark Plug Guide and Information

After a friend got quoted over $100 per spark plug, i was curious!
So the hunt began
--- Stock NGK Spark Plugs ---
 p# LKR8AP which suits a stock M3 2008-11 (4.0L V8), M5 2006-10 (5.0L V10), M6 2006-10 (5.0L V10)

 Multi-Ground Plug
 12mm Thread Size
 26.5mm (1.04") Reach
 5/8" (16mm) Hex Size
 Platinum Tipped Center Electrode
 .035" (0.9mm) Gap
 Heat Range 8

--- Going Colder with $60-$100 Plugs ---
LKR8AP (stock# 4471) is a heat range 8, I believe you can go 9 or a 10 which are
R2556B-9
or
R2556B-10
* note that NGK use a higher number for colder...
apparently on avg every 75-100hp increase you go a step colder.

For a G-Power Kit (note that it is rumored they use 2 steps colder than stock):
R2556B-10 - 12mm Thread Size, 26.5mm (1.04") Reach, 5/8" (16mm) Hex Size, .028" (0.7mm) Gap, Heat Range 10
You can sometimes find a set of 8 for sub $400 (e.g. on Nengun)

R2556B Series is a racing plug, where as the original is multi-ground. A racing plug cost ~ $100AUD each
Racing Plugs PDF:
Background Information - see here
Stock Numbers - see here

---  Going Colder with HKS ---
HKS make a plug, the XL type spec are below:
XL Type = XL Type φ12x26.5mm 16mm

HKS Plugs Lists

These are the same plugs evo X people jump to when going colder.
Some regap due to misfires

M40XL 50003-M40-XL - NGK8 equivalent SUPER FIRE RACING M40XL 50003-M40-XL
M45XL 50003-M45-XL - NGK9 equivalent SUPER FIRE RACING M45XL 50003-M45-XL

These are commonly used in Mitsubishi EVO X 08+ (4b11) and Lancer Ralliart
Stock Evo X Plugs are a ILKR8E6 which is a heat rating 9 and gapped at 0.6mm
Looking at NGK they were originally released with a ILKR7E6 which is a heat rating 7 but they must of then started used the colder plugs ILKR8E6. Maybe varying differences in enviroments?

The older Evos ran a - Long Reach Type φ14x26.5mm 16mm
http://ayu452.blogspot.com.au/2012/06/research-into-colder-plugs-z27ag.html

---  Going Colder with Brisk --- 
ER12S
BRISK ER12S is a special racing spark plug that BRISK Supply to European Rally teams such as PRODRIVE and its thermal value is equivalent to NGK heat range 8. (NGK Racing Spark Plug R7437-8) BRISK Silver Racing Spark Plug ER12S is also performance upgrade plug for Denso IKH24. Primary use: The BEST PLUG for Forced induction (Turbo, Supercharged..)

ER10S (1 step colder than the ER12S)
BRISK Silver Racing ER10S Spark Plug 14mm thread, 1.04"(26.5mm) reach, 5/8'(16mm) hex, gasket seat, non-projected tip, resistor, fine wire 1.5mm Silver center el., Cut-back ground electrode (performance upgrade for NGK R7437-8 and/or ILKR8E6 and/or IKH24)- EVO 9, EVO X

--- M3 E92 G Power ---
My friend has a gpower supercharger in his M3, they wanted to charge him $100 a spark plug LOL
What a joke.
Thanks to google  i found and clarified the above info

ps. i cam across mentions of G Power not telling people the part number but saying they will resell them the @ $125+

M5 People:
"I sent G-Power a message asking if they could just tell me the part number for the plugs they use as they do mention they run colder plugs with their systems. Today they replied and wow, talk about rip-off!!! They replied stating they would NOT tell me the part number but they would sell me plugs. Apparently because their "engineering costs are so high" they can't just pass info. They want 125 Euro/$166 per plug!!! I found the NGK plugs that are 2 steps colder for $45. For G-Power to sell a plug for almost 4 times as much tells me their services/mods are probably priced accordingly!!!!!!!!!!!!!!!!!!!!!! G-Power will NEVER get any business from me!"