WHY...
the SE/SP stuff is better, its fully adjustable for a start and can easily be rebuilt it only cost me £70 to have my SP unit rebuilt by K-tech in coalville and it came back gleaming and with a new remote on it.
If you look in the suspension bit it even states on the site that the R spring is longer than the SE one and makes a good upgrade, i can second this as i have done it and i will lay my ass on the line and say that my revamped SP shock with R spring performs as well (as my untrained ass can tell) as my Maxton shock on my NC29.
mate i would seriously consider keeping the SE stuff and putting the R stuff on the other bike when you sell it.
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MC21SP - Roth-tax
CBR400 - track
MC21R - sold
MC21SP - sold