06/07 Megabomb difference?

FMF has a different part number ( 044227) for the 2007 YZ450F megabomb than the 06 which is part # (044140).According to their website,the 06 also fits the 03 thru 05 models.I purchased a used 4.1 system with the megabomb on ebay but was sent a megabomb for a 250f.(seller blamed it on his son?)(According to FMF the midpipe and muffler are the same on the 450/250)After a few phone calls (and an extra $100) I gave him back the 250 header and he got me a brand new megabomb (06 part number).I couldn't get a straight answer from the tech reps at FMF and am waiting on an email reply as to the reason for the different part numbers.Its not a fit issue as I know the 06 will mount on an 07.If its a performance issue,I don't want to run this new header,so hopefully I can exchange it.Sorry for the long post,anybody have an answer?

Im guessing its the pipe size where the header connects to the midpipe.On my FMF slip on it came with 2 different insert depending on what header I was running.For the record I am running a megabomb off of my 06 on a 07 slip on 4.1.

Thank for the responce aedwards07,still no answer from FMF.It may be the pipe size where they connect ,although I would think its the same.I did hear that in Dirtrider mags 450F comparison test,someone said they liked the megabomb with the stock muffler,but my megabomb does not slip into the stock midpipe(midpipe is 1 3/4 inch,megabomb is 1 5/8) I'll have to keep trying the tech guys @FMF to see if I can get a straight answer.I know for 07 the muffler opening diameter is at least a 1/4 inch smaller than the 06(quieter)so it seems strange that the 07 midpipe would be bigger.Any other answers or input out there is appreciated.

I believe my 06 midpipe is smaller than my 07 midpipe.Didnt your header come with spacers so you could run the megabomb with the stock midpipe?Mine did.

Its a used (06)FMF 4.1 muffler / midpipe off ebay.Makes me wonder if the 07 version has different size tubing?The megabomb he got for me is for 03 thru 06 according to FMF's website.Doesn't really make sense as Yamaha changed things in 06,and 07 is the same.I assume I have a comlete FMF system made for the 06 but mounts on the 07 no problem.If there is no performance difference from the new 07 system then I'll just install it.Just don't understand exactly why the part # is different on the 07 header.3 days and no response from FMF techs.I'll just have to call them again.To answer your question,there was no sleeve included to mount to the stock muffler.A friend with an 07 got a used 06 system that bolted on fine.I rode it(only a lap)and was not overly impressed by the power gain,but rode another with the new Pro-circuit TI system and it seemed stronger throughout.

Just talked to a tech rep at FMF named Tony and he said there is a slight bend difference for the 07? (these guys don,t want to spend much time on the phone with you)He also said there will be no difference in power with the 06 pipe on the 07.(hope he's right/honest)I know others on this forum have said good things about the system.I guess I'll just try it on Friday , and report back.

Just wondering how you guys like the power characteristics of the FMF compared to the stock one. Also, how far does the end pipe stick out past the number plate, comparatively?

FMF doesnt stick out near as much.Here is a pic of my bike so you can tell.


That's a good couple of inches shorter than the Big Gun.

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