Yeah, it depends on the engine and what nitro % you use also.
In previous engines (SH.28 & Mach .26) I used to run MC9's with 30% and they worked fine.
Then in the P5, I found the OD99 to be a much better plug then the MC's.
Now in the V-spec, the OS turbo plugs that seem to last forever, Im on my second gallon with the original plug