the good news here ..... the K-28 4 Ohms woofer is a drop in replacement for the K-24 8 Ohms woofer and so is the K-107 Titanium large motor tweeter , the K-28 is around 100$ a pop , all this , while keeping the HII crossovers , the K-53 mids driver can be upgraded with a TItanium diaphragm , the end result , more bass , and clear HF.