after testing tons of plugs in my os .30 vg this is what i found.

#1 odonnell 99,makes the best power
#2 duratrax gold,wider power ban
#3 os r5,the 99 is far supior
#4 os a5
#5 os a3
#6 duratrax carbon speed

after my testing all i will use now is odonnell in every aplacation.i was really suprised that it was so much better than the r5,way more power and crisper idle,the duratrax gold was a suprise too good gas miliage and a wider powerban.GO ODONNELL!!!!!

You do understand OS engines run a shorter plug then others! I hope you are running the O’Donnell 99OS plug. Here is the chart.
http://www.odonnellracing.com/glowplugs.html
The only thing I do not like about O’Donnell plugs is they are taller then many and some igniters will not fit on them properly. [X(]

yes i run the 99os.im not that green.thanks for looking out thoe.i use the purple hpi igniter it fits perfectly.