Hey, don't forget to actually keep your endurance too.
I just spent months building up muscle, I now weigh a lean 96 kilos. Due to work commitments I was off the bike for about 8 weeks. I got back on the bike a few days ago thinking 'I'll still be fast due to the extra muscle'... Nope, I'm slower, painfully slower and it felt like my lungs were being stung by 8000 bees. The extra muscle alone did f_ck all.
Build muscle by all means, but don't forget the endurance.
now, I'm going to get the endurance back... I've left it a bit late, track season starts here in Australia any day now...