Magnum 24
 

This is probably the boat you're referring to. Found these quotes on the forum. Magnum Marine made a 23 and several 25, but never a 24.

"And here is ANOTHER variation of the Shadow/Apache, but with major changes. We used the Apache 22 hull as the plug, but widened the pad, widened the strakes, changed the angle on the strakes, widened and changed the angle of the chines, lengthened the boat to 23'8" and made it 8'4" wide - the result was a very fast 24 - This is the boat that Dan wanted to imitate, but he never made any running surface modifications for the bigger/heavier load."
"We originally named the company Magnum Express and built a stepped hull prototype in 1985, but were "politely" asked to change it...so we renamed it Tantrum Marine for the production boats and I believe there were about 20 boats sold the first year and a half. The boats ran very well. Boat was manufactured by Magnum Express Powerboats, at 750 Copans Road, Pompano Beach, Fl. In business approximately 5 years, building the Tantrum 24 only. They were not from an Aronow or Magnum or Cigarette mold of any shape or length or kind. The new, never used, hull mold was purchased from Bob Saccenti @ Apache Powerboats & a Magnum Express deck was tooled. Apache never made a boat from the mold. The beam was 8'4". It had a pad bottom, stepped transom & reversed chines & ran exceptionally well."

You Tube

.

I aquired Magnum Express Co.in a package deal in the early 1990's(?). I purchased a new bare hull for a Bahamian customer and was offered the entire co. ( molds, templates, licensing, ect) for a minimal cost. This bare hull was rigged with triple 200 mercs and ran 100+.

So only in name form was the "24' Magnum express boat" associated with a true Magnum hull........very interesting! The yellow ob boat looked a little like the Ghost boat from Freeport L.I.

.....one of the best East Coast production O/B boats.....28' K & K Ghost!!

https://cimg8.ibsrv.net/gimg/www.off...bc4dc4a649.jpg
Here is a original 24' x 7' beam Magnum that raced out of Great Britain.

Aronow's Harry Schoell designed Magnum 23 was built in two examples. The single inboard and this outboard one. Supposedly they're 23'6" x 7'. Here's the outboard courtesy of OSO signature Mange.
https://cimg5.ibsrv.net/gimg/www.off...87af6da588.jpg