All bottles used with my Torpedo leak, even Specialized. Anyone find this one from XLAB really “leakproof” or is it smoke & mirrors for advertising?
I’m not sure what’s with your bottles, as I’ve never noticed a leaking issue with my horizontal setup, but give the Camelbak Podium’s a shot.
Like I said, I typically used Specialized bottles & never had an issue, but now have switched to some of the Camelbaks, with the always-open valve, & I like them alot.
Try a Camelbak Podium bottle. I’ve not used it on my aerobars, but the valve system is pretty good at preventing leaks. These bottles don’t leak in regular bottle cages:
(They are around $9/each at REI)
http://www.camelbak.com/sports-recreation/bottles/podium-bottle-24oz.aspx
The camelbak bottles are great but after a while they leak up front too, but I have found a solution for all bottles… put a strip of white plumbers tape on the threads and that will help ALOT. But I prefer the CB bottles still.
I have had a problem, too, with bottles leaking - both while mounted horizontally on my aero bars and on an angle on my down tube. The leak is coming from the threads not the valve.
I’ll have to try the plumber’s tape to see if that helps. I don’t mind if it is water dripping but it sucks when it is HEED or G2.
Camelbak Podium and Xlab bottles don’t leak from their threads in horizontal setup for me. But they do spew some liquid every now and then through the jetvalve if I leave that open. It’s not a lot but it makes me have to wash the sugar/salt residue off my bike…just another reason to have a front faring over your brakes! 
Thanks for the responses. I own a Garmin Camel Podium bottle & it is the best one I have for now. The specialized do leak from both the thread & spout. The Camelback is pretty decent–but the XLAB looks (and claims) to be good as well (as it should especially for the price). Will have to look into. Tired of cleaning sugar coated front brake each ride.