autrichon gris
Registered
I think you may have misread 4m for 40m. The old jetstreams were prone to fluttering if tuned incorrectly at the surface, but the Xstream design is much more refined *same guts, but a different case design*. I'm not a huge fan of their mouthpieces, but if you like them then happy days. If you decide you want to change, look at the Comfobite mouthpieces sold by Apeks. That's what I have on mine and they fit the Poseidons with a little bit of persuasion.
Thanks for the tip. I re-use my Jetstream for the first time in years, and i their original mouthpiece is sh.t. Will try with the Apeks Comfobite, which i like on my Apeks XTX 50.