With the last EFRA AGM the members spoke out their concern about the 30xx exhausts and because the 35xx exhaust have the same design the members expected the same problems. Due new designs which will be introduced from 2011 on it was the choice to go on with the 20xx/25xx design of pipes.

Regarding this one, I think the new 353 has different timings and so they finetuned the exhaust to it.