shahinian- I took my stock SG seat 2 weeks ago to upholstery shop and had the sides shaved and perforated pleating added to it and backrest pad ($250) with 2 day service. I've posted this before . . .
Normally it is not hard to find a stock seat on ebay. I bought one last fall for around $140 and sent it to Mean City Cycles for an upgrade. Good luck on your search!