Foam too hard At the beginning of every project , we tell customers that we make foams on the firm side to achieve a good finish and provide longevity due to softening. I think when you start the conversation this way , fussy customers are far more receptive. Your not pulling the wool over their eyes as it’s just a fact that the firmer the foam , the better the finish. If you look at modern seats , they are like concrete but are designed so well with regards to shape/lumbar etc that they are comfortable I have to admit that it’s hard to achieve Ergonomic comfort in a lot of classic Americans due to cabin size and layout, I guess it’s up to us to get this point across. We always push the point that the softer(more comfortable!) we make it, the less crisp it will look over a period of time . I think that’s a fair and genuine approach.
We’ve never done it ourselves but I’ve seen people cut holes out of the base and used webbing I guess to add softness/bounce . I would imagine that holes by themselves would only act like breathers ( which is no bad thing!) and aid the cover to return but without adding softness which you require.