If you are debating whether or not to get the 520 upgrade then the short answer is YES...get it. If you want to know why you should, continue reading...... I was unsure if the expense would be worth the investment, after all the GV125S in it's self is a decent cruiser and with the stock sprockets I could achieve 67 mph if the weather was on my side. I found it slow getting there all the same and at top end the bike would be hurting.....you could hear that she didn't like being redlined. I contacted Hyo Riders and Marcel was so helpful in arranging the upgrade I needed. Once fitted I noticed I was up to speed much, much faster than previous and the gearing and revs seem more in tune. I find that 4th can be a cruising gear....enough pull to get you along and when needed take you to 60 mph , I only really use 5th for when I'm on open carriageways. I have achieved a top end speed with this conversion of 75 MPH and considering I am 12 1/2 stone , the bike has panniers and a topbox and I am fully kitted when riding, I think that is impressive from a upgrade. At this stage I'm sure I have covered most of what is needed to know.....and in fairness , the promises made as to what this 520 upgrade would deliver have been spot on. Well done Hyosung Riders 10/10. Again a big thank you to Marcel for all his help in this, you are a star....

Just upgraded to the uprated coils, the uprated regulator, the uprated stator and ngk caps with iridium spark plugs. I have to say it made an amazing difference, the bike almost no longer needs choke (less than a minute and only on first start in the morning), acceleration has improved significantly and my bike is now charging (which was my original problem :p). Very happy with all items 🙂 Bike is a 2003 gv250 carby model

All round great piece of kit now got my top end back with smooth gear changes a must have replacement for the stock gt125r 2016 models ones very happy

Straight swap, easy fit. Looks great. Will post pictures later. Bigger front and rear sockets, longer thicker chain. I am perfectly happy with my purchase and hand delivered by Marcel. Excellent product, great store. Will be using again

Look the mutts nuts , and Marcel had them delivered quickly

A great companion to the coils and caps. Highly recommended. Fast delivery to Spain. Excellent service from Marcel

Came to Spain very quickly. Excellent kit. Spain being a bit naughty with customs since Brexit, or it may be because I use a private post box! Not bad though as I had €100 of parts and they only charged €10.

This absolutely out does the standard horrible Korean stock. Easy to fit, although you do need to clamp the joint on the other side firmly to avoid leaks. Great upgrade and well priced.

ordered a red set and they are better than i expected perfect fit no messing and quality is spot on recommend for every hyo owner 😛

Fitted yesterday, seems to be working well, Delivery by royal mail arrived on time, Very well packaged with other items ordered, Very pleased