I used Dayton Audio film caps in mine, bypassed by 1 uF paper-in-oil and 1 nF teflon for shits and giggles (both russian military NOS). The form factor of the Daytons helps it fit in the Crack case pretty well I think and the price is reasonable compared to some alternatives. Fitting all the mods in there is challenging, my suggestion to those that want to supermod their Crack is to make use of the ample vertical space. Once you've installed film caps in the output stage, there isn't much left to work with. The Dayton caps will even fit with their long axis perpendicular to the chassis plate, if you're careful about how they're mounted. That's how I also fit a choke and a 100uF power supply cap in there as well. I think the diodes are a great upgrade, but dwarfed by the impact of the choke and some simple power supply cap bypasses. In any case, I would recommend doing the film output caps first as those are going to be hands down the biggest upgrade. Keep in mind that the film caps take a couple hundred hours to burn in and sound their best, they are a bit stiff and stale at first but the increase in detail and clarity should be immediate.