Putting aside the gal you say complained; gals see all shapes and sizes and pretty much know how to handle whatever you can dish out.

To go and "warn" them beforehand may seem like you are being disingenuous or trying to impress them unnecessarily.

Most providers have magnums on them anyway and you should have some with you just in case.

I don't see the purpose in letting her know the size of your equipment other than to brag and potentially scaring her away.

Thanks for the input.  That was my initial feeling as well.  The two providers I've seen thus far in the US have mentioned it but didn't have a problem accommodating me.

you could get an email alias that mentions your large size. Admittedly this can come across as being a bit cheesy, but can be a way to let a lady know that she should plan on having her own Magnums around when you visit. And as someone else pointed out, always be sure to bring your own. A good provider should always be prepared for such things, but it can't hurt just to be sure. Bringing your own lube can be helpful too (another thing a lady should already have, but just in case). Lube can be a life-saver when dealing with larger clients, especially ones who last quite awhile.

Yes, say something!

I'm apparently the odd one out here, but yes size matters a lot to some of us *cough cough* and not all of us are physically able to enjoy the magnum guys. You may "scare off" some ladies prior to meeting, but that's a GOOD result for you -- if a lady can't accommodate you, wouldn't you want to know that well beforehand as opposed to halfway through the date? As you know, that can lead to a disappointing evening, to say the least.

Save yourself money and time, and prevent frustration, and find a delicate way to let her know you're on the larger side. Emphasis on "delicate" here! "Hey, baby, I'm tall, tan, toned, and ready rock your world all night with my GIGANTIC PENIS!!!" is not the way to go. "I do want to disclose that I've been told I'm larger 'where it counts' by other ladies. If this is an issue for you, I understand and wish you the best. Otherwise, I'd love to proceed with setting up a time to meet." is a bit more tactful.