First of all is Ian on holiday or taking a break from whistle making because I have had no reply from his email address.
Second is if you have an impempe whistle can you please describe its playing characteristics. 
That’s it!
John
I have an Impempe nontunable D.
It’s an easy player, not very aggressive in terms of volume, but ideal when you are just playing a tune on your own or with just one or two others.
It’s a pure-toned whistle, and handles similarly to a Burke or a Hoover.
Intonation and balance between the octaves is quite good. The whistle is quite comfortable to hold and play.
Here’s what mine sounds like:
http://flutesite.com/samples/sirius_imp.mp3
–James
Thanks for that James, my Bb arrived this morning! It is lovely. I’ll add photos and description to this post later!
I have one with a C & D tone tube. Not only is it a great whistle, you get some cool postage stamps too.
I have 4 Impempes, a high D, C, Bb and F.
See also the topic ‘Impempe whistle impressions’, and somewhere on C&F there’s a whistlereview.
What are the characteristics and how do I like them? First of all, Ian is a great guy to deal with, he’s quick in answering questions and sending the whistles. He has his own website: impempe.mysite.wanadoo-members.co.uk
The whistles are VERY solit with a thick wall and also a wide bore.
I read that the volume is low, well especially my D and F have a very high volume, comparable to eg. Susato. thing is, the bores are all the same, so, the lower the whistle, the lower the volume.
The magic thing about Impempe is that whatever is said about the volume, the sound is so much focused that it can be heard miles away, better than a violin.
The sound is also not pure, but round and complex, a bit more flutelike.
It’s very responsive, more than my Sindt D and it easily goes from first to second octave.
The bellnotes are very round and clear, with the C and Bb you have to underblow, but from the second note on this is not problem.
All in all, GREAT WHISTLES! I love 'em!