the subox mod doesn't always play well with other toppers, specifically... the fixed firing pin has been the cause of a number of those issues... hypothetically, there is a v2 in the works with a spring loaded firing pin...
you COULD put a crown
tank on it... not sure about performance, though - with the .25 ohm coil, i tend to run mine at 50-70 watts... with the .5 ohm coil, should be in the power range for that mod, though... and for what it is worth, the crown is an exceptional
tank setup - rivals my tfv4's for performance, and a bit more user friendly