Tamada is down near the mid 1:56. That's compared to the best lap recorded by the Superbikes in the low 1:01. The MotoGP guys will still improve and a high 1:55 could be possible. So maybe a good 5 seconds difference is about right.
Also interesting is that the 600's are less than 3 seconds off the Superbikes. The 600 winner would have finished 13th in the first Superbike race, ahead of Chris Walker, both Petronas, and Ben Bostrom. Imagine that Foggy's bikes are slower than the TenKate 600 Hondas!