I know that problem can't print too fast or I get the same issue.
However it was not always speed for me that causes it...
partial nozzle clog or a piece of filement stuck in the ptfe tube has the same effect.
Did you check if both are clear?
The sound is basically the extruder gear that is slipping. I will do the same noise (or mine did) if hold the filament by hand so that it can not pull it.
Also check if your spring has not slipped, some people had that issue, especially with the upgrade kit.
About the warping, if you have the option try a glas plate do that or try a brim instead of the raft? The brim will help agains warping and the surface finish is better than with a raft.