06 YZ450F spark arrestor and repacking

[bikinrob]

I need to repack my silencer, and I need a sparky for racing.

On repacking - i can get a Moose kit for $10 but when I look at the Yamaha OEM replacement it's $210.00. What gives?

On the spark arrestor - tough finding one for this model but I found a PMB for $134. Looks like for double that I can get an entire new muffler. Not that I have money to burn but should I just upgrade and solve the fiber and sparky problem and possibly get some performance gains or am I missing something?

Going the complete oposit on the sparky, can I order a replacement insert from another manufacturer for under $20 and just modify it to insert into my stock pipe - or is there some tuning considerations I'm ignorant of?

Thanks