Hey there , my 2 cents .... I just had some questions on my 357 not long ago as I had not owned one before but had many others. I ported transfers , deleted gasket ( used permatex motoseal) and as for the muffler mod , drilled out the center baffle with a larger hole and added a gill on the side at the seam. I do not care for running any screens on my saws. I was very impressed with the power it now makes ! A great thread you can take notes with is : mastermind revisits 346xp ....