About the 160kts to 4 DME.
As an approach controller, if a pilot is not happy with the 160kts till 4 DME and wishes to do a different speed I am happy to oblige as long as they're not already on final (depending on traffic)
If you give ATC the heads up early on they have time to adjust the sequence, allow for vortex etc, according to your speed.
OK, some controllers are more helpful than others and some airports are just far too busy but it can't hurt to ask.
Don't ask, don't get.
