I've been getting my hand at 8-string guitar for a good 2 years now, and having a good intonation has always been a nightmare on this particular guitar (a fairly cheap Ibanez RGA8). I have tried many, many, many different string sets, combination of sets and tunings (from F#BEADGBE over CGCGCFAD over EADGCEAD and variations, for those interested), each time spending hours on adjusting bridge, saddle, even the trussrod if needed.
After slapping these babies on, I could go back to the regular F#BEADF#BE tuning I prefer lately, the intonation was just perfect from the get go and I didn't have to adjust anything on the guitar. I did however have to drill out the hole on the machine head to have the 8th string pass through it (and yes, I knew what I was doing), so you might want to double check the gauge of your 8th stringhole.
I've had them on for a couple of weeks now and barely had to tune them. They still sound fresh, even after hours of chugging, picking, slapping and tapping all over the neck. My guitar sounds punchy, ballsy and the low end, which has always been hard to tame, is tighter than ever. They sound especially full and rich on my JCM-900 tube amp.
All in all the best strings I've ever acquired for this guitar, definitely will buy these again.