Optimized PCR system for the amplification of long or GC-rich DNA templates. The system includes an ultra high fidelity KOD DNA polymerase and quickly and accurately amplifies genomic and phage/plasmid DNA targets up to 24 and 40 kbp, respectively. KOD Xtreme Hot Start DNA Polymerase successfully amplifies challenging DNA templates with up to 90% GC content. Each kit provides 200 U KOD Xtreme Hot Start DNA Polymerase, an optimized buffer and dNTPs sufficient for 200 amplification reactions.