I have tried both the Acerbis 3.0 and IMS 3.0 tanks on my 2017 crf 450rx. I purchased the Acerbis first because it cost a little less, and I had seen the IMS tank and felt that it didn't give adequate space where radiator cap sits. I have used both brands in the past on other bikes and didn't have a preferance. After installing the Acerbis tank, I was very disappointed in just about every aspect of the tank. To sum it all up, it was fat! No other way to say it. at the back of the tank it pushes the shrouds out about an inch wider on both sides than the seat. The bike felt like a Harley. Unfortunately, until I finished the install and put the seat back on, this didn't become obvious. I thought I would give it a day or two to see if my opinion changed before taking it off. The next day I sat on it again and immediately removed the tank and ordered the IMS tank. Before putting the IMS tank on, I set it next to the other tank and took a couple of photos of the 2 tanks side by side and end to end. this confirmed just how "fat" it is. I installed the IMS tank and was very happy with everything about it. My concern with radiator cap clearance was not an issue. Bike did not feel any wider than stock when sitting on it. Everything fit well and tank looked like it was a production part of the bike, instead of looking like a bulky afterthought. My only disappointment with the IMS tank is that if I wanted the removable gas cap assembly so that I could use my dry break set up when racing, it would have cost $80 bucks more. The Acerbis gas tank came stock with a removeable gas cap set up (which does work with the IMS dry break). I love the IMS tank for this bike and although I generally like Acerbis products, they missed the mark on this one. I can't believe they didn't put a little more development into this tank before putting their name on it and putting it out there for sale.