Alright, I don't own a power bomb, and Queen, neither do you. So here is the description and the link to the FMF Power Bomb :

The redesigned PowerBomb is a four-stroke header that incorporates FMF’s patented PowerBomb module at a precise location in the initial stage of the header. By positioning this “Bomb” at a key point in the system, increased performance and flow is achieved through the expansion and contraction of exhaust sonics through the system. Result is a flow increase of nearly 10%! The outer chamber in the Powerbomb allows the air to expand, cool and ramp back up at a higher velocity. Additionally, the PowerBomb is a “pre-muffler” of sorts which helps to lower the bikes sound output by providing more sound absorbing surface area for the sound medium (exhaust gases). On some models, you can choose between a moto or supercross version. The supercross version is designed for more low to mid-range power where the moto version is focused in the mid to upper RPM range.

Products - MX - FMF Racing


The header length, size, (and additional "shaping") affect TRQ production (therefore fueling requirements) ...
A simplistic explanation is velocity vs volume - that, for a given length, larger dia's slide the TRQ curve higher in the RPM - Smaller dia's move TRQ curve lower... If these dia. changes are optimized for a given engine better than the stock header, you get enhanced TRQ curves as well.. The megabomb shape is the current technology for creating an enhanced TRQ curve that starts low in the rpm range and extends to the very top end -the best of both a large and small dia. header..
There is also the size/shape of the midpipe -the pipe coming off our silencers down to the header joint - they are an extension of the header and therefore should be considered part of the header "system".. The DG-R I own is obviously designed to carry the same(or very close to the same) dia. of the stock header almost all the way to the silencer. Without going into the details of how/what this does, suffice to say this setup makes tremendous TRQ and throttle response starting all the way down to about 3500rpm, but is "done" by the time you get into the low to mid 9k rpms at WOT...

 

I tend to not believe everything a company tells me in their marketing literature.

Meanwhile, here is a detailed article with decibel readings from various systems including comparisons between identical slip-ons with Powerbomb and Megabomb. The Megabomb is (as stated in forums all over the net) 1-2db quieter than the Powerbomb. 2010 Exhaust Pipe Buyer's Guide - Dirt Rider Magazine

 

Went thru that article,,,,didn't find anything about comparing identical slipons with the power, and then mega, bombs.. Not saying the powerbomb does or doesn't lower the racket, just saying FMF says they both do and that I have not seen tests showing otherwise.. I am certainly the last person in the world that would put faith in anything "stated in forums all over the net".. I'm more the "prove it or present overwhelming evidence" kind of guy.. Since we don't own Power Bombs and I know of no testing data I can share, I can only present the FMF description..

 

Hi Klxster

OK...so I'm ready to order again. I'm going with the Q4 (not sure about header yet). I've already rejetted to 140/2N, DJ kit 2152 & have the airbox lid off.

Without doing the MSM at this time, what will adding the powerbomb header do for performance (little/large)? Would I need to go to the 144/1N without MSM. Remember, this is a woods bike. I'm not concerned with street worthiness (only use road to get between trails).

I've tried to sort this out myself with reading, but I keep getting it turned around

Thx Kevin

 

Ok Kevin, lets see if I can get you on the right track without writing a novel..
The MCM does not require a change in a "known" setup in a good running carb. For instance: The MCM works great on a %100 stock bike, I mean one with no other mods at all.

My induction system setups for max power work with or without the MCM.
It is not wrong to view the MCM as the last item on a performance mod list. It is also not wrong to view the MCM as the first item on the mod list - I did..

You are already setup to make max power with a slipon. You will need to redo the setup to 144/1N if you add the Powerbomb.

While I have not tested a Powerbomb, I feel confident that it will show similar results to the Megabomb with perhaps less TRQ production in the low to mid RPM range. This means the power above 5-6k will be strong and get stronger all the way to redline (10.5k) - below 5-6k, not so much.. I am rarely below 5-6k offroad, if you ride like me then expect to see a big increase with the powerbomb vs stock header - If you want numbers, probably 1-2 HP more throughout the upper range (6.5-10.5k).

 

Awesome information....thx Kevin

 

We haven't talked about your offroad skills or whether you'll be riding "2-UP" .. So,,, are you fast offroad? Gonna take a friend with you on single tracks/rough stuff ?

 

I haven't had a dirt bike in 30 years. I've been riding Harley's for quite a while. Plus I mountainbike quite a bit.

My son just got his first bike, a 2014 KLX250s. I fiqured I'd try trail riding again with him. I used to be pretty good at it, but as I said, quite a few years ago. We have a lot of single track around my area, so I plan on doing a lot of exploring, geocaching, etc.

 

Ok, well then unless you want to just get it all done at once(header and 144/1N), the Q4+140/2N lidless will put your bike WAY ahead of the '14 in power levels and make good usable TRQ/HP from about 4k to a little over 9k - maybe as far up as 9.5k.. Knowing kids - I have 3 plus I'm still one myself,lol - you'll be relegated to riding that '14 as soon as he gets a taste of that hot rod '07..

BTW, I have 2 Harleys, 1 Indian, 1 Victory, 1 Ducati etc , in my "little" 11 bike collection..

 

From the article
2010 Exhaust Pipe Buyer's Guide - Dirt Rider Magazine

This shows a reduction in volume using the MB (by roughly 1db) in two of three different sound tests with the same bike and slipon.

I also found a youtube video several weeks ago with someone measuring decibels while comparing OEM header, Megabomb, Powerbomb with OEM exhaust and Q4. Can't find it again.

When my Chinese Megabomb arrives I'll perform a similar test and post a video.. for science.