The choice is up to you. Compare some of the specs:
Magnecor 8mm Electrosports 80 Ignition Cables
OVERALL LEAD ASSEMBLY
Outside Diameter of Cable............8mm.
Colour...........................................B lue.
Boot/Terminal Configuration.........Various - to suit different applications worldwide, as well as
customer special requirements.
Country of Manufacture.................Cable: USA. Assemblies: USA, UK and Australia.
CABLE
Construction Type..........................Silicone rubber insulator, re-enforcing braiding, high-tear strength silicone rubber outer jacket.
Insulator Material...........................High dielectric silicone rubber.
Outer Jacket Material....................Extreme high-tear strength silicone rubber.
Heat Resistance.............................260o C (500o F) service temperature.
Dielectric Strength....................... .55,000 volts.
CONDUCTOR
Conductor Size........................................1.75 mm in diameter.
Conductor Type..........................................Magn ecor Metallic Inductance CN20 RFI and EMI Suppressed.
Core.............................................. Ferrimagnetic base over Kevlar.
Windings.......................................48 turns per cm (120 turns per inch).
Windings Material.........................Chrome-nickel.
Resistance.....................................98 ohm per cm, 3K ohm per ft. + 10%.
Capacity.........................................5 5,000 volts, 2kVA.
TERMINALS
Spark Plug.....................................Stainless steel snap-lock 180o bendable and fixed 90o styles.
Distributor and Coil........................Brass, stainless steel and beryllium snap-lock 180o and 90o styles.
PROTECTIVE BOOTS
Spark Plug.....................................Silicone 205o C (400o F) - selection of straight, 45o and 90o styles used
where applicable - special connector assemblies for some applications.
Distributor and Coil........................EPDM or Silicone - some sets will be fitted with OE style connectors.
Magnecor KV85 Competition 8.5mm
The KV85 conductor size (for lack of a better term, the internal wire size) is about 45% thicker in diameter than the 80 series (2.5mm vs 1.75mm). Resistence is reduced about 25% (2.2kOHM ft vs 3kOHM ft. There are other differences you can compare for yourself. Ultimately, you have to decide whether or not the price difference (about $10.00) is worth it.