I would probably go the Lucas route as Ti has done to avoid overloading the cats, risking a blockage. I've stuck with just using Shell gasoline and easily get 120,000 miles on plugs, went 260,000 miles on O2 sensors and am still on original cats.

2002 X5 3.0 311,000 miles
2014 428i 22,000 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird - Under restoration