Here's a quick list of (6.5" - 17cm) comps and full range co-axials that will fit the K11 (all models) without issue:
Feel free to add any others you may find also.
Components: (6.5" - 17cm)
Alpine SPE-17SF Shallow Mount
FLI Audio Integrator COMP6
FLI-UNDERGROUND-FU6-COMPONENTS
JBL GT5-650C
Vibe LiteAir 6
Full range:
Ground Zero Radioactive GZRF 16FX
Infinity Reference 6532si Shallow Mount
Infinity Reference 6032si
JBL GTO -6528S
JVC DRVN CS-V627
JVC CS-HX637
JVC CS-V626
Vibe Slick 60 v2
Zero ZX6
FLI-UNDERGROUND-FU6
KENWOOD-KFC-E1752
Feel free to add any others you may find also.
Components: (6.5" - 17cm)
Alpine SPE-17SF Shallow Mount
FLI Audio Integrator COMP6
FLI-UNDERGROUND-FU6-COMPONENTS
JBL GT5-650C
Vibe LiteAir 6
Full range:
Ground Zero Radioactive GZRF 16FX
Infinity Reference 6532si Shallow Mount
Infinity Reference 6032si
JBL GTO -6528S
JVC DRVN CS-V627
JVC CS-HX637
JVC CS-V626
Vibe Slick 60 v2
Zero ZX6
FLI-UNDERGROUND-FU6
KENWOOD-KFC-E1752