I've done US to Intl in about 10 mins and do not recommend it. That was to the gate, where Zone 3-5 was boarding and the Z1/2 line was empty.

Was in J. I don't see there being a faster way without a concierge, golf cart and skipping even more than we did. And even then I think 7 mins would be pushing it, even if your driver was leaning on the horn and doing a Sandra Bullock impression to maintain speed.

Oh and this was D7x. 24x gates are YYZ you can add a chunk of time.