Need a 3s 4900mAh 20C lipo
 

Does anyone know where I can find two 3s 4900 mAh 20C lipos??

Does it need to be exactly those specs or can it be similar?

The only one I've found is the FP Evo-20 4900. Here's a good resource page:
http://www.progressiverc.com/3S_Lipo.html

Is it ok to use a 20C 2s and a 25c 3s battery??

It's not recommended, but you could probably do it if you used a LVC on the 20c 2s pack, but I would probably use one on the 3s also, just to be safe. The LVC on your ESC wouldn't work because the 20c pack's voltage would drop more than the 25c pack.

Thanks Jerry. The only ones I have found are from MGM.

Novak has them also. <a href="http://teamnovak.com/products/price/index.html#modules">Here</a> is a link with the part numbers or you can buy them from the product details page.

Thanks I meant 20C 3s 4900mAh packs.