Oval slip-on with a new Quiet Core insert?

[quadman21]

I have had my sport series oval slip-on on my 05TRX450R for over a year and it works great. It's an awesome pipe. But I purchased a quiet core insert to tame the sound levels. I was running a 180 main jet with 5 1" holes cut in my air box lid. Now I hust can't seem to get my jetting right. The quad just got sluggish and slow form the bottom to midrange. It behaved like it was bogging down. So I changed my main jet to a 178 and turned in my fuel/air screw about a turn. It's better but it's still not the same. It doesn't have the snap it had before and still seems bogging or a little sluggish from about 1/4 to 3/4 throttle. I even tried lowering my needle one more notch. That put it at the last notch and it was so lean it wouldn't run without the choke. So does anyone have any suggestions or setting ideas?

[Mike/HMF]

Don't expect the same power the engine was producing before the quiet core installation as it will cost some power. Adjust your fuel screw to the highest smoothest idle. Turning the fuel screw in 1 turn will likely lean it to the point that it wont run without the choke applied. The main jet is only being used from 3/4 - WOT so if its running ok up top dont change the main. Usually a major jetting change is not required with the addition or removal of a quiet core insert.