+1 on all the shim stuff above. Just be careful not to take the 1 x thin .1mm copper shim out too soon. Make sure you have fully broken in the motor and it can be turned over by hand in the buggy when hot before you pull the .1mm shim out, especially if you are going to be running 30%. Best to also run a medium plug or cooler (say OD 97T or LRP #6) if your going up to 30% with this shim removed. Depends on your ambient temps of course.
Enjoy your racing. Glad to hear the GO GX's are doing the business.

+1
Tho I don't use the break in shim, i just make sure to heat the engine before i start it for the first few weeks of racing.
The 2009 MG66 I ran stock shimming for its whole life span (62 litres) but I just pulled 0.1 shim out on the 2010 MG66X after break in for a little more punch.

& how are the AKAs (on the rear) handling the extra punch ?

I've bought a GX-7R combo set to try out.

Which is better on the engine: the 2072 pipe that comes wit the kit or the Aplus 0801 which ive got aswell.
What are the characteristics of the 2 pipes (top/bottom)?

pretty well, it's the fronts that wear first due to unloading to the front with less weight up front wheel spin.

They both have the same length headers to the best of my knowledge.

The 2072 is designed for the GX Series motors, and does perform exceptionally well, especially on the 5 and 7 ports.
I have seen the A Plus 0801 on a 3 port and it was fine.
Personally I would run the 2072 for maximum performance right through the power band, but try them both and see what you think. A lot will depend on track design, driving style etc too.

I have sold quite a few 2072's to guys who run Alpha and JS engines, as they outperform the pipes that come standard with these motors hands down.

Thanks Grizz, i'll do some testing

1 alloy 0.3 mm + 1 copper 0.1 mm is required for 30% nitro?
I've used three gallons nitro 25%, with 0.5mm shim!

thanks!

just leave your shimes as they are for now (0.5mm) with the 30% & see how you go !
& you might want to think about replacing your rod aswell to get the most out of it . JMO

LOL i use a dead rx battery, cable tied to my front bumper, work ok until you hit a bump in the track then up she comes

Today me and my two teammates swept the track today with 3 GX5R motors @ Arc Raceway in Temecula, Ca for the Halloween Club Race!.... I took 1st in Truggy and my teammate clint took 3rd....then my other teammate took 2nd in Buggy....it was a great day for Go Engines

good stuff rob, well done
go the GOs

NICE WORK

anyone looking for gen5 5port engine. i have one with maybe 2gals at most for 65 shipped. For pics search profile

Just a heads up, the novarossi carb retaining lock fits the go engines perfectly. They are the same as the ones that come with the gx r series carbs with the o-rings. I broke one last week and bought a couple nova's as replacement. They are about $3/ea on ebay if you search for: Nova Carb or use the following link: http://cgi.ebay.com/Novarossi-18000-...item3a594c475f