09 yz450f: what adds more, megabomb header or q4.1 exhaust?

what one adds more.. FMF megabomb header vs stock header?

or FMF q4.1 can vs stock can?

I want to compare your guys answer versus those of my local shop.

they said the 09 has a very restrictive exhaust. so if you replace the stock exhaust you will notice a huge difference.. so my buddy forked out the 600$ for so for the FMF q4.1 can... is that true?

they said that the changing to a megabomb header is a waste of money/insignificant.. is that true?

theyre basically saying that changing the can is more effective than the header... I always thought it was the opposide way around? the header did everthing and the can barely did anything?

thanks.

ditch the stock can. I swapped out my stock pipe for a 4.1 and had to change up my work out routine. The power was noticeable for me and really woke the bike up, coming out of the turns.

They make q4.1? How does that work?

They make q4.1? How does that work?

sorry. I meant to say q4

Oh I gotcha :smirk: I've seen that combo a lot lately. Can't tell you how the Q4 is but I know the megabomb is pretty gosh darn good.:excuseme: Could always try a powercore/megabomb combo...

If you listen to MXA, an aftermarket exhaust is worth its weight in gold for a 09 YZ450F with 4-5 peak HP gain. (I don't have a dyno and they had access but :excuseme: )

With that said...a 4.1 and a Q4 aren't comparable. Do you need power without sound restrictions for MX (4.1) -or- below 96db and a sparky (Q4)?

my buddy wants the q4 as its supposedly the racing one with a smoother powerband (I think)...either way he ordered the q4.

just a bunch of power hungry fools who ride forestry.

Not exactly the info you are looking for but I put the Q4 on my 08 and it helped some, but did not come close to meeting my expectations. I ordered the powerbomb header about a week later and both together made a huge difference. I can't say that the header made the most difference because I think it's a combo deal. My thoughts are that the stock header and can are a poor functioning design and neither will work well by just replacing one of the components. If this is the case, then whichever component that you replace last will seem to provide the most benefit.

The stock '08 header is a very large diameter to work with the restrictive OEM muffler. It may have been a particularly bad match for the Q4 for some reason, but lots of others have added different kinds of slip-ons and gotten big improvements from it.

Still, a full system will produce the best results. Good report on your experience.

I have heard the 08 header/exhaust for the yz 450f (maybe even 250f) were pretty good.

but the 09 exhaust is terrible. super restrictive.

I have heard the 08 header/exhaust for the yz 450f (was) pretty good.
You heard wrong. Almost anything you replace it with will add 5 hp at 5500 rpm.
You heard wrong. Almost anything you replace it with will add 5 hp at 5500 rpm.

yes I know aftermarket will improve any stock pipe.

but what I meant to say is that the 08 pipe gets a 8/10 rating.

and the 09 pipe gets a 4/10 rating. (so restrictive)

yes I know aftermarket will improve any stock pipe.
Not that much. The biggest improvement in peak power over stock on an '06 YZ450 that I recall seeing was 1.6 hp, but that pipe also trimmed the low end. Anything more than that is quite rare. Occasionally, a bike like the '08-'09 YZ450, or the '05 RMZ450 comes along that becomes the exception.
... the 08 pipe gets a 8/10 rating.

and the 09 pipe gets a 4/10 rating. (so restrictive)

By whom? The two systems on the '08 and '09 YZ450 are fundamentally identical, and have both been shown repeatedly to have a huge soft spot right at 5000 rpm.
Not that much. The biggest improvement in peak power over stock on an '06 YZ450 that I recall seeing was 1.6 hp, but that pipe also trimmed the low end. Anything more than that is quite rare. Occasionally, a bike like the '08-'09 YZ450, or the '05 RMZ450 comes along that becomes the exception.

By whom? The two systems on the '08 and '09 YZ450 are fundamentally identical, and have both been shown repeatedly to have a huge soft spot right at 5000 rpm.

oh ok. maybe I read/remember wrong somewhere.

I thought I remember someone here once said that the 08 yz450f exhaust is fine, but the 09 is very restrictive. I dunno. I dont own the bike. its a friends bike, just trying to help him get more power, and save money.

You mentioned a YZ250F. There may have been some differences between those two that you heard about. I haven't kept up. But there's very little difference in the '08 and '09 YZ450's. In fact, the '09 is supposed to be improved and less restrictive than the '08, but that may be more marketing than anything else.

The '07 stock exhaust was "OK", and the '06 was a good pipe, other than it's long and heavy.

You mentioned a YZ250F. There may have been some differences between those two that you heard about. I haven't kept up. But there's very little difference in the '08 and '09 YZ450's. In fact, the '09 is supposed to be improved and less restrictive than the '08, but that may be more marketing than anything else.

The '07 stock exhaust was "OK", and the '06 was a good pipe, other than it's long and heavy.

oh ok cool, thanks for the info.

I must have misheard or gotten confused somewhere along the line.

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