First off let me start out by saying I am not new to bikes. I have had many comp bikes for years and then when old enough I gravitated to the roads with street bikes of all kinds. The last bike I owned was a WR250x. Great little bike but its not a 450. I spent much time with the power commander and made a great map but still the power wasn`t there even after all the typical mods. When a 2014 Wr450f came up for sale with only 190 kilometers I stuck the 250x up for sale and went after the 450. The kid was selling it because he had bought it for a yz450 like his buddies had but found it lacked power stock. He never knew about the throttle screw or plugged up exhaust. I can understand why...the bikes throttle only turned about 1/4 of the way. When I got the bike home I took it for a romp around the yard and noted the throttle issue I read on here many times. I never rode it again until I pulled out the throttle screw and went to the local nut and bolt shop for a much shorter replacement. The only other mod I did was remove the spark arrestor and smaller inner exhaust tip. I did notice from the quick ride around the yard that the exhaust had gotten really hot, more so then I am used to. I figured it was due to the choked up exhaust everyone spoke about. I went to work and removed the end cap off the muffler and saw proof of my suspicions. Here is what I found...notice the discoloration in the stainless. This is a sign of excessive heat caused by the restricted muffler. Behind this sits the spark arrestor where two tiny holes dump exhaust from the middle chamber of the muffler. Heres what that looks like... and here is the spark arrestor.... After these few items were quickly accomplished it was off for a test drive with new shorter screw in throttle body and muffler end gutted. There is a night and day difference with the bike. Stock form front end could barely lift off the ground and now its a wheelie machine. Like its smaller sibling the 250x these engines make there power high in the rpms so lack of throttle explains the difference. The muffler isn't as hot either. Now I was happy with the bike. I called up a couple riding buddies and off we went for a spin and I introduced the new girl to her new BFF's a sexy little 09 KTM 400 XCW and a MILF status 06 RM250. Testing would have to wait as the KTM blew a rear tire about 10 kilometers in and we had to hobble back to the trucks. Up to that point the WR ran as good or better then the other two. Top end neither the RM or KTM could keep up on the dirt roads. Ride #2 I gased up the bike and called up the old man and we went on a 65 kilometer round trip from his back yard, me with my WR and him on his atv on a wide range of trails from steep washed out rock covers roads to grassy bogs to fast woods roads where trucks drive no less then 70km/h. What I noticed is the bike on slow trails where your creeping 20 km/h or less tends to get very hot. You can see the antifreeze boiling in the catch can underneath the left rear fender. When speed picked up and air starting moving thru the rads everything went back to normal. Just before we got back the fuel light went on at 65 kms. Read the manual and that puts the fuel remaining at 1/4 tank when the light goes on. My fuel range is about 87 kilometers per tank. I expected better. Not sure how the Yamaha fuel injection is programmed but my Polaris sled will start dumping fuel if the engine temp rises in an effort to cool down the engine. So I suspect the bike may have been doing that but some of you guru's might be able to chime in and set the record straight on this issue. The 65kms we travelled took 4 hours so most of the trip was slow going. Plus the atv had a harder time picking thru the trails and I had to wait often. Overall I was very impressed with this bike and can see me keeping it for a long time. I also ordered the GYTR competition ECU. Can anyone tell me if it comes loaded with a map or do you need the tuner right from the get go? I figured the latter. I have read on here that everyone saw a difference once the ECU is installed but it also comes with the new shorter throttle screw so I wonder if they only notice a difference from the screw itself!!! Can the airbox be opened up air more? I did a Frogzskin Airbox mod to the Wr250x and it worked out great. Think I might try it out on the 450 as well when I look at it better. Here is a link to what I am talking about that I started on another forum for the Wrx....http://wr250rforum.forumotion.com/t9357-frogzskin-airbox-mod Can this work other then removing the snorkel?