I'd go with the splice first, as it gives you a little more aggressive acceleration and releases the top end. One you're happy the motor is running well like that, then do the next mod.

White plugs means the motor is about to expire - or has!

Tan is good, and black is safe as houses, but you'll feel it's running woolly if they're black.

Wet plugs can cause a misfire, and is an indication that the plug is not burning all the fuel - possibly ignition problems.
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball