The speakman heads make it pretty easy to remove the flow regulator. This won't do shit if you don't have more than the regulated flow rate though...but most places do so you should notice a difference.
I got one of these
for $9...but I would not recommend it at any higher price. It is not the same as the normal speakman heads. There is very little adjustment, really you just alternate between the outer spray nozzles and the inner massage stream (which I don't really like).
Instead, you would be better off with the classic models where the lever actually adjusts the flow. You probably won't actually adjust it much, but it is nice to get a setting you like and keep it there.
If you have low water pressure issues, I might suggest the 4-nozzle model
over the standard 6.
If you take ones of those and remove the flow regulator (and probably even if you don't), you are going to get more percieved pressure. There will be less total streams of water coming out, but the flow rate will be about the same so each one will be higher pressure...you'll get the same amount of water but it will push harder and faster.
The other option would be to try out one of those laminar flow heads. They make it feel like you have more water coming at you. They don't get steamy like a normal aerated shower head though...so if your bathroom is chilly, you might find that the air in the shower stays cold (but at the same time it doesn't get the bathroom all foggy and wet).