the only way to stop mouth breathing is to tape the lips, roll lips inward and double tape back on both sides to form 2 tear off strips

Have you actually tried this yourself, isn't it uncomfortable? What type of tape is used?

if you want to get CPAP benefits, just do it.

Mitch, personally I don't believe in taping your mouth but if your going to you use that thin medical tape not sticky tape. Our jaws are so strong, no matter what you do, if your a mouth breather you will breathe through your mouth. I know you said you don't want to use a FFM but it maybe your only alternative. I use one and a chinstrap to keep it all in place, it's not that bad when you get used to it and you get the full benefits.

Taping works for some but ,after looking into it, I don't feel it's right for me. I've tried some adjustments to how I wear the chin strap and it's helped to significantly reduce the incidents of mouth breathing. The nasal pillows are so comfortable for me that I sometimes forget they are on, so I'll try some further tweeking of the chin strap fit. Thanks for the responses, they are very appreciated.
Mitch

there are various kinds of chin straps. the ones that my supplier started me out with were flimsy and did not hold enough pressure to my chin. Now, the red or maroon chin strap I use looks like a wrestlers head gear, and this one really is strong and firm enough to hold my jaw in place. The order number for this kind of chin strap is TMS-09S.

I also have a mouth guard for TMJ, and using it helps me not to grind and clench my jaw at night, but seems to keep my mouth in a more stable position, too.

Seekinghealty101, thanks for the information about your chin strap. It looks more promising than the one I'm using. I'll check with my DME or maybe get it on-line.
Mitch

Mitch
just an fyi, I think the last letter "S" is for small, and might be M, L for bigger sizes. The small is really tight and I have a large head! But that is what keeps snug the best for me. I had a medium before, and just as headgear stretches out, so do these.

But, I think this is the best of the models that I tried. Best regards!

I switched from fullface to nasel.I first had a chinstrap similar as a big velcro wrap. I drooled sone so I had to keep it washed, Next I have a blue cup lik strap that I pit on outside my headgear and get an edge to stick to it. Works well for me.

I checked out seekinghealty101's TMS chin strap and ordered a TMS-09ADJXL. It seems to be working much better, for me, than the Respironics model I was given by my DME. The DME doesn't provide the TMS so I bought it online for 19.99. I ordered the ADJ (adjustable) because I could get a better fit. Following the online head measurement instructions I did not order the XL and it didn't come close to fitting me. They sent me an XL at no additional cost.

The chin strap will keep your jaw in place, but I found that I was still opening my lips which let the air out. I switched to a full face mask instead.