Hiding User Agent or Spoofing it? How to?

Hi guys,

im trying to build a custom audience with Facebook advertising and trying to use their pixel and cloak it - everything is fine, im able to call it once I make a conversion on my actual money page by making it look like when a user visits my "thank you for subscribing" page, but the problem is that my tracking platform when calling conversion shows "iMobiTrax API" - I would need to spoof it or clear it?

How to do that?

What would be perfect is - I could make the call from my own server with some application or I could spoof it to look like MailChimp or etc, cause this API wont do it for me atm

Maybe you can create a php script which calls your pixel, with php you can set any useragent you want.

There are methods to do spoof or blank the referer but the problem is there is no foolproof way of doing this without leaks.