There are 3 to choose from now.
*&* @ www.wbodystore.com
Primaries are slightly longer than others and the outlet is 2.5" Great for midrange and great for the price but leave sliglty less potential w/ the 2.5" outlet.
SLP'* @ www.intense-racing.com
These are probably the best out there now. Although I have heard of a chronic ticking problem with the flex section. The outlet is 3".
Donkey Punch Racing @ www.donkeypunchperformance.com
They are similar to the SLPs but were designed for an easier fit into the luminas and old monte carlos. They have a 3" outlet also.
And IMO TOGs were the best untill they started to get shady and went out of business. You may be able to find them in a for sale section.