What do you all think about the power bomb and power squar iv-2 combo

FMF is misleading everyone by claiming their Power Core IV-2 is quiet. It is 5 decibles lower than the power core. There is at least two people on this site that are quite unhappy with their FMF systems. I was going that route but for now have just pulled the insert out of the silencer. The power gain is definately worth the noise. It MIGHT be a little louder than an aftermarket, but it is FREE! There is a tech-tip to install a 90 degree bend, automotive exhaust tip. For $5.00, it directs the noise downward and ensures you don't have water running into your exhaust system. At present, I am still looking for a viable option, mainly a tunable system to compromise between noise and power. Plus you can add more disks for power when you ride in an area where nobody cares.


99 WR

I am not a FMF employee, but I do like the company, believe they provide a better quality product and service than some of the other big companies, ie Pro Circus. Anyways everyone is bit*ching about the marketing ploy over the powercore IV squared and that its no quieter than stoke, well here is a direct quote from there website: (fmfracing.com)

How quiet is it?

Although no aftermarket system will ever be as quiet as stock, you'd be surprised at how quiet the Powercore IV-Squared is. When installed on a Yamaha YZ426, it's 8 decibels lower at idle and 7 decibels lower at 1/4-throttle than last year's FMF muffler.

Per there own quote and advertising they never claim it to be quieter than stock. That would be difficult because stock exhaust is so choked down. Maybe we should all read things first before we start pointing fingers.

Just my opinion

I ran my PC-IV-2 again today on a 80 mile dual sport loop. Since the Power Bomb header is still not availabe I'm still running the exhaust with the stock header. It is loud but not as loud and my e-seris pro meg with 12 disks. The PC-IV-2 has excellent low end and mid range but the pro meg is stronger on top end. Probably 4-6mph better top end with the promeg. The PC IV-2 perfroms slighly better on the bottom and mid range and would be a little better trail unit.

I just wish it was quieter. At least with the e-series you can knock down some of the noise by removing disks but you also remove performance and I did not like the performance at all with less than 10 disks---best performance with 15disks especially on top.

The problem for me with either of these pipes is they cannot pass sound checks at 99-101db. The only pipe so far I tried which can is the FMF MegaMax II with 9 or less disks. The FMF MM II also comes with a quiet core which makes it totally civilized but with less power, at least you can get there. The FMF MM is a good all around system.

If you ride desert or don't care and are of the ride loud and proud group then DSP or Yoshimura are great systems.

I will be trying the Stroker SX-1 next. I think it is the most promising from a noise and performance stantpoint but I will make no statements about it until I personally tested it. Who knows I may be totally disappointed or elated time will tell. You can add a quiet tip to the Stroker to quiet it down a little more.

O'well the noise vs performance debacle continues. Hopefully I will have something quiet enough by the end of the month or I will be SOL for riding in my favorite summer riding area because they sound test all the time and if you don't pass you don't ride. I want to be sure before I drive all the way up there in my motorhome only to be disappointed. Who knows I may be buying another FMF Mega MaxII.


FMF Fan (Airastro),

The simple fact here is that FMF has been using misleading marketing statements right up to the point that this muffler was released, and then no doubt decided to admit the thing is barely quieter than every other muffler due to customer compaints. If you have been following the PC IV-SA ads for a while here's what you would have read as these are direct quotes from FMF's previous propaganda: Dec 99 Dirt Rider pg 64 "The fact is, under acceleration the PC IV-2 spark arrestor is as quiet to the ear as a stock WR400 exhaust with all the stock restrictors intact, yet outperforms the stock unit." Maybe the ear they were talking about was one with earplugs in it. Here's another from a more recent Dirt Rider: "The FMF Power Core IV-2 SA is the best performing, and totally sound friendly exhaust system made for dirt bikes. AND, you don't lose power; you gain!" Sounds quiet to me! And another point to note is that FMF obviously scrapped the "FMF wing" for the "powerwave". You can only imagine how loud the old design must have been. As far as the "power bomb" is concerned, I'm sure that its release has only been held up by the fact that it doesn't hold up to any of the claims made by FMF. They will probably need to rename it "performance bomb" and then after its release than can call it "sales bomb" because after this huge delay and false claims nobody will buy it. Anyway enough bitching about FMF.


By the way, I got tired of waiting for FMF, so I bought the Big Gun (tapered headpipe) system for $260, and it is as quiet as stock with the baffle in (at least when I have earplugs in it is).

[This message has been edited by Brad (edited 05-13-2000).]

I just bought the Suppertrapp IDS2 and love it.It was boxed like a T.V., came with a turn down tip and a open 2in tip like the FMF,12 disks,S.S.pipe,and fit like it should.I got the quite core.The sound with 3 disks and the turn down tip is not to bad.I can ride on the street without turning heads.The disks are inside and it looks great. Price $189 at Rocky Mountian.The performance is what you make it,quite and no topend or loud and a broad power band.The pipe is very adjustable.

Is this worth the $480? What should I expect from this setup? I think I heard that the Power Bomb pipe is not avail. Is this true? Is there any other pipe-silencer setup I should consider? Just got my bike 2 weeks ago and have put about 200 miles on it. I love it! What other upgrades do you all recommend? I want power, comfort, and looks.

Clark...Please keep us posted on the sroker SX-1.I ride the drz 400 and im interested in the SX-1,but Ive heard nothing about it from a riders standpoint.Thanks.

[This message has been edited by Tennessee Thumper (edited 05-16-2000).]

Clark mentions the Mega Max. What kind of performance did you get with that pipe and what sound levels were recorded. I would be interested to know. I currently run the White Bros E series and inserted the quiet core. I barely made it at 101db's with 7 disks. Ranger said I could ride, lucky me. I am concerned about jetting at this point. Rest of my bike is stock and I ride at about 2500 ft. How does 5-7 disks effect jetting. Anyone know?


Does anyone know if the Megamax II is still available for the WR? The FMF website doesn't list it for the YZ/WR, but does list it for several other bikes. Has anyone seen it listed anywhere else?

Its still available but remember it is not a race pipe but a good all around pipe that can be made quiet without killing the power. I liked it for everything except wide open desert running.

Call one of the big outfits like Chaparral, or a major dealer. If you buy it through a distributor you will pay less than going directly to FMF.


I kicked up my gearing to 14/47 using the PC IV-2 to take advantage of the excellent low end and mid range power. It was perfect for dual sporting. Easier on the the rmps for street and great on dirt and fire roads and little tall for trails but perfect for my rides from my house. A quick change to a 13 counter and at 13/47 which is 1% lower than stock and with the PC IV-2 low end great for trails. I ONLY WISH IT WAS QUIETER. I can not wait for the Power Bomb header to go with it. Time will tell.

The pipe is not quiet, but performance is good so unless the Power Bomb really quiets down the combo I will not be able to use it in the areas where they sound test.


[This message has been edited by Clark Mason (edited 05-14-2000).]

The mega max II is a great pipe for everything except wide open desert or closed course motocross. It does not have the same power at the very top end. It is great every where else and is very tunable for noise vs power. With 9 disks is has good power excellent low end torque and was tested a 99db. With 13 disks it runs at about 103db and has great power.

With the quiet core in and 10 disks it is quiet and still has reasonable power.

I rode with the pipe and the FMF ceramic coated header and used 10 disks and rode everywhere without worring about what it sounded like. Dual sport out of my garage, in the national forests, etc.

The pipe has a little smaller core than the PC IV and a longer and larger muffler canister. With the stock side panels the fit was excellent, however, when I got my Carbon fiber side panels (which fit tighter to the bike) the muffler would not fit. So I sold the entire system. This may have been a tactical error on my part.

As a side note my 99 WR with WR timing and the MM II with 10 disks was just as fast as my friends 98 YZ 400 which had a e-series running 10 disks. The MM was much quieter. This was demonstraded in a number of drag races in which neither bike had a clear advantage.


Has anyone tried the Vortip insert on the

stock muffler? A riding buddy of mine has

one installed on his '98 XR400. It is louder

than stock, but not bad at all. I'm curious

as to whether the Vortip would also work

the same on the WR.

I have the Vortip insert. It is very quiet but greatly reduces the power. Especially low end. I even cut all the baffles off and just ran the down-turned tip. I took it to a field and wore ear plugs (so I wouldn't be fooled by the extra sound). I ran with the insert in, without, in, out. It definately reduces power. But, it is nice and quiet.



Bryan, I'm assuming that the Vortip lies somewhere in the middle between the stock baffle and the open pipe for sound and power, am I correct. If it has better power and is more quiet than the baffle it may be worth getting. I have to been PC at most of the places I ride.

Has anyone tried the Baja Baffle? Here is what Baja says about it:

"The stock WR muffler is extremely restrictive with the stock baffle installed. If you remove the baffle the stock exhaust goes from a respectable 94 dB (A weighted, 20 inch test at 5000 rpms) to an extremely loud 104 dB...The "Baja Baffle" features all stainless steel construction, is polished and requires on repaking ever. It uses tuned unequal length tubes to effect noise cancellation. It brings the noise level down from 104 dB to 96 dB yet produces nearly identical power to the open pipe."

I really want to find something to use while I wait to see what becomes off all these new pipes coming out...

JJ in WA

Yes JJ, that is true.

Actually cutting the Vortip baffels off and just running with an open tip that points down works pretty well. But it's 85 bucks.

I think Mikes home made $5 job would work best.

This weekend I tried the Stroker quiet tip. It is a bigger opening than my modified Vortip and has a turned down tip. I loved the sound! It's pretty quiet at idle but gets louder as you give it gas.

I rode with it for about 3 hours at Woodland park. This riding area has lots of cool trails and all types of terrain. But, it isn't too aweful technical. After 3 hours of riding with the quiet tip, I loved the sound. But, I was getting frustrated because it seemed I was climbing steep sandy hills in 1st gear that I normally would climb in 2nd gear. I thought it was just me being a wimp since I haven't ridden in several weeks.

Finally I switched bikes with Jake (I wanted to try his big-ass seat foam) who has stock WR timing. HIS BIKE SEEMED FASTER THAN MY YZ TIMED BIKE! ! ! Especially at low rpm's.

At this point I still didn't suspect the quiet tip so I rode with it all the way to lunch. During lunch I thought, I wonder if that quiet tip is robbing my power?

I took the sucker off and rode without it the rest of the day. Sure enough, I had my torque back and could climb those steep hills in 2nd gear and I was using 3rd a lot more. The bike just flat out lugged much better.

So, I'm betting the Baja tip does the same as all the others. It'll quiet the bike down but at the expense of a little power. If you want full power, open pipe baby. If you want a quieter ride and don't mind a slight sacrifice in power, the Baja tip might work and the Stroker is probably a little better.

Like I said, Mike Trains $5 option is probably the best for quieting the bike down at idle but retaining power. If you buy the tubing he recommends, it's a bigger diameter than all the others including the Stroker tip.

By the way, Big Jakes big-ass seat foam is awesome. And Jake hit a big tree with his shoulder and headlight and head and the tree suffered more damage than big Jake. NOW THAT'S BIG!


[This message has been edited by Bryan (edited 05-15-2000).]

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