There's a bunch of SPF parts for sale that were in the McMichaels (Atlanta SPF dealer, now closed) inventory. I'm sure sidepipes were on the list. Contact the Commissioner (user name) here on CC for details. You can PM or email him, hopefully from this link.
http://www.clubcobra.com/forums/member.php?u=21683
If the link doesn't work, just do a search here for user name "Commissioner", then do the email or PM thing.