whistling brewgroup

[floydpink]

I'm just wondering if anyone experiences a high pitched whistle when pulling shots from their machine?

I tend to pack my portafilter pretty tight and grind fine in order to keep my shots about 25 seconds long on the extraction.

I've sorta figured out a system to give me a 25 second pull and yield about 2 ozs,

Anyway, I seem to also get a whistle, more often than not, once the pump starts and occasionally even get a little squirt from the top, regardless of how tight the pf is on.

I'm guessing it's not a huge deal but am wondering if it might be overworking the pump?

I'm also wondering if I might be overthinking the 25 second rule and should ease up a little on the tamp and dose......