We cut out DS' nap at about the same age...he was worse though, if he had a nap he got such a recharge from it he would be up until 10pm-10.30pm without fail. DH and I couldn't stand it.

We found that in the early days of cutting out the nap, there were some days DS just couldn't get through the day and needed his nap because he was too tired and cranky, but gradually 4 days with a nap became 3 days, became 2 days, became 1 day then maybe once a fortnight he would need a nap and so on - like a watch that needed re-setting! This was easy enough to live with, having him up late wasn't such a pain if it wasn't EVERY day.

For a while there, while he was getting used to not having a nap, on the days he didn't have a nap I would give him his main meal at lunchtime and he would have toast or something for dinner (by 5pm at the latest) otherwise he was too tired to eat properly. And because I knew he'd had a decent meal in the middle of the day I was more relaxed if he was a bit too tired and cranky to eat well in the evening. We did find bathtime could be a bit fraught if he was very tired so within reason we did handle him with kid gloves between 5pm and 6pm, because he would be so tired at that point that if he started crying he wouldn't stop till he was asleep.

We found that by cutting out the nap DS was actually getting MORE sleep. If he didn't have a nap he was getting 12 hours sleep and would generally sleep through. If he did have a nap, he was only getting 9 hours sleep, and would wake up during the night. That was enough to convince us that we were doing the right thing.