These guys are not in the Ft. Lauderdale area but we have had there risers on two boats now and have worked really well. Similarly they have supplied risers for many boat owners with Cummins 6b at another forum we have been on these past 20+ years with good reports.
Dave at Greenwater exhausts
Marine exhaust systems in Riviera Beach, Florida builds custom exhaust systems. Make sure that you follow Tony Athens design criteria: minimum of 12" of rise above the water line and a free draining mixer.