What's the better method to transfer the circlips to the new headpipe?
TIA
Hinzy

 

Spread the retaining rings, remove and transfer to the new header.

Lock ring pliers (external snap ring pliers) make this an easy job, but it can be done manually with 2 sets of pliers or vicegrips (one on each end). You can also work it around with a large screwdriver to separate the lockring and work it around the flange.

 

Snap ring pliers are the way to go. The kind that are "duck billed" would be best for this, but I've made the round style work.