i have a lefty ibanez gsr100 with ghs bass Boomers gauge 50-115. i have a heavily modified ibanez grx20 guitar which i play in drop c tuning. by using the zakk wylde (11-70) i can acheive drop c no problem. both guitars were recently set up by a local luthier and i told him i wanted them both set up for drop c (cgcfad for the guitar and cgcf for the bass). on the bass the low c is floppy. should i get a 5 string set and use the BEAD string and tune up or is it ok the way it is? just answer the question about the string gauge please don't try to convince me to get a 5 string bass. i'm not getting a 5 string cause i play lefty and i'm perfectly happy with 4. a 5 string lefty would be hard to find and too much money and i don't want to buy another bass right now. just wanted to get that out of the way.