I am in the process of converting a 3.3 as well. What has been said to me many times is that the stock diffs will not hold up long to 5s power, which is what I will be running. Hence, Mike sells hybrid cases which work w/1/8 gears. They are not cheap, but, on 5s I would seriously consider them. If not the hybrid cases, at least AL inner and outer cases w/hardened gears which will reduce flex a lot.
Welcome to the madness!
1. MBX-6 T8 1900KV, RX8 ON 4S
2. MBX-5T 1520, MMM ON 5S
3. MBX-5 ONROAD CONVERSION 1515, MMM ON 5S
4. MRX-3 ON ROAD CONVERSION 1512, MMM ON 6S
5. TEN T 2650 T8, MMP ON 3S