For N/A & Turbo engines ranging from bone stock to hard-core race. The ultimate in plug performance, max yield, all (4) plugs will use a matching heat rang, the most potent spark, high output, long electrode life, complete burn, about the cost of platinum, superior, requires a thin wall socket to install/remove.
#1 BR7EIX (x4) Mainly City Driving, N/A only, No porting but high performance, 7 Heat.
#2 BR8EIX (x4) Mainly Highway Driving, N/A only, No porting but high performance, 8 Heat.
#3 BR9EIX (x4) City/Highway Driving, Street ported N/A, Non-ported Turbo with slightly increased boost & bolt-ons , 9 Heat.
#4 BR10EIX (x4) City/Highway/Race, BridgePorted N/A, high boost turbo, 470 HP, pump gas, 10 heat