Ron,
Not doubting that at all, but it does appear that Webercarbs, Redlineweber, TEP and TWM are all intimately related, if not owned by the same interests as Sandy pointed out.
Inglese Induction Systems and Pierce Manifolds Inc. appear to be separate from the bunch above. Although, Inglese is no longer a separate company but is owned by Total Performance Inc. a hot rod conglomerate. It certainly looks like there has been a lot of consolidation within the performance parts industry as in many other types of companies. Pierce Manifolds, in Gilroy CA - hey Patrick D. want to give them a visit for us?- seems to be a independent. They do distribute Mangoletsi manifolds which are made in England though.
The only name I don't see in your list is Kinsler in Detroit, but they are strictly fuel injection and don't distribute Weber stuff. They also cater to the racing world and are somewhat pricey as well. But, they do know about GT40s; as I have related here before, the senior Mr. Kinsler owns the GT40 that GM bought in order to reverse engineer it. Kinsler, a one time GM employee, bought the car in boxes for next to nothing at a plant surplus sale.
Regards,
Lynn