Higher c rated lipo's do I really need them?

[quincey]

I'm gonna be purchasing some new lipos for my sc10 and dex410r but which ones do I buy?... I could buy cheap 25c stick lipos which I bought last year and ran to great effect but I think they are holding the power back,I could buy some Orion 90c lipos but do I really need 90c and what's the deal with 90c compared to the reedy 60c,I'm an average driver in terms of where I finish but at the last buggy meeting my car lacked pace I'm thinking either motor or batteries but the batteries are beginning to bulge so I'm taking it that they are goosed,I could do with some advise on which ones to use and where to get them from...