Question?

I have a 87 300SDL, I had the leathers re-done, but didn't change the horsehair pad, When I get in and sit down the seat is bouncy, not bad but not like what I want it to be. My mom first noticed it she had a 91 560 and she didn't remember the seats being "like a trampoline" Also the seats were a different pattern, I thought they may be made differently, Im looking on ebay for seats from a 89-91 Sclass they are the firmer kind? I know they will fit and I can have my leathers changed over, im just wondering if anyone knows if the inner design is different making them much firmer. What made me think to ask was when my friend came over today and showed me a car he was interested in purchasing, a 95 E320, last of the Mohican, and I plopped down and it was so nice and firm, like wise was the back seat? Just like the seats of the 89-91 s class.....