I know exactly what you mean and I agree to some degree - I think though there is a difference between a 'HiFi music lovers' definition [and needs] of basshead and an 'Audiophile' definition [and needs] of bass. They dont necessarily contradict but maybe you can say one may lean towards more quantity and one towards more quality?
Ive had the same thought popping up the last few days about modding. Ive done a fair bit of headphone modding over the years and technically the same principals should apply here.
One tiny example - trimming the bottom from foam tips to give deeper insertion for the EDP+ Bringing the drivers closer to the eardrum gives more low end
But what Im thinking of is perhaps using some Bass filters Im not going to use and modding by perhaps adding a tiny extra hole or maybe covering up any holes of the less bassy filters
Ive also been thinking about the foam in the treble filters. I have lots of different types of 'studio' foam knocking about. Could be fun