TEST REPORT - DOUG HENRY (DSP) Carbon Air Box with Velocity stack

G'day All,

What a busy week and weekend I have been having. I know there are some of you who have been awaiting this report, so here goes.....

I will list in terms of: Finish, Quality, Installation and Performance.

1. Finish - Beautiful. Well presented and well packed. The Carbon is spotless and the areas that are exposed to the elements are covered in a clear platic film to prolong the look

2. Quality - I would rank it as good. This will be explained in the Installation area.

3. Installation - Ouch, this is where the **** hits the fan.

a). HOTSTART - The standard airbox has a nozzle for the Hot start. GONE. The hose for the hot start is changed. The hose from the Carb to the airbox is removed. The outlet to the carb is covered. The inlet to the hotstart is left dangling with a piece of filter foam zipped to it.

:). Boot Mounting. You need to basically loosen the entire subframe, remove the pipe, brake assembly, rear fender, etc.

c). The rear fender holes do not line up correctly. Need to redrill the hills.

d). Number Plates, Side Panels. These do not mate correctly either. The right side is not too bad, although not the best fit. The left side (from the perspective of the rider sitting on the bike) is completely attrocious. It sticks out like a saw thumb! I may need to do some cutting to the side panel. A question arises. What is the difference in frame, airbox and side panels between a YZ and WR?????

4. PERFORMANCE - YEEAAHHHH BABY. The bottom end performance is incredible. The performance curve is basically flat. Perfect and smooth from the bottom to the top. Smooth and powerful. The first time I tried it after the installation I almost flipped the damn thing. The bottom end is incredibly beffier and the mid has been improved also. The top is virtually unchanged, although it does feel smoother. The velocity stack is tappered, thus the significant improvement to the bottom end.

The performance sensation is very much like a road bike. All the way from the bottom to the top, the power is smooth, uninterrupted and virtually instentaneous. The throttle response (ie. the ability to built revs) is vastly improved. Not like a switch, butcertainly improved. The DSP Carbon Airbox with velocity stack and the DSP Pipe and header are the perfect match if you want power everywhere. WOW...

My recommendation - If you want low, mid and top, it is a worthwhile investment.....


Oh, one more thing.

Did I mention that the power is ARM pulling... :)

For those of you who would like more power that includes: Low trunk pulling power. Mid range wheel lofting hit. Top end desert screaming attitude. Then go no further.

Dont buy the KTM, does not compares interms of engine performance

Dont buy the husaberg, it'll blow at the first rock.

Stay blue, but invest in the airbox.... Trust me. It feels like a street bike when you wring it's kneck.



You left out the baaad part: How much will it put us Yanks back in U.S. dollars $$??


99 WR, all YZ mods, de-octopused, OEM YZ tank and seat, jetting by Clark, fork job by Pro Action.


For clarification: WE'LL be having a KICK ASS time in Moab!! Right Mitchy & Bill?!!

Estimated pricing....

Airbox - US$425

Pipe and Header - US$500?

So, all up, about US$900+

The carb settings are: 180, 48, 2.25 turns out


This is all very interesting since I have only ridden my WR with this air box, the DSP CF box, installed. I also installed a Yam Ti YZ subframe right from the get go! I must admit it is a pain to get the carby off must lossen the two lower subframe bolts, remove the top subframe bolt, lossen the carb intake manifold clamps and rotate the entire subframe back to pull the carb. I am getting good at it since I ride a large variation in altitude.

Damn I wonder what my bike would have felt like stock--probably would have been real disappointed and sold it flat out.


Hey Clark,.

Maybe the YZ and WR subframes are different. I was wondering, what did you pay for the Ti subframe????


Since I purchased most the cool stuff at the same time I bought the bike new, MONTCLAIR Yamaha cut me a real sweet deal on the extras and I think I paid about $350 US for this individual part. Its hard to tell as I was going for a great package deal which I got with all the CF / ti /rad guards / clutch levers-purch / IMS seat tank /BBR R brake lever / Pro-Tech Kick starter / Baja Kit, etc. at the time of inital purchase. Hell I knew more about what was available for this bike than they did and they sponser Ty Davis. I still set the record as far a s MONTCLAIR Yam is concerned for the price on a new dirt/street legal bike, they were happy and I was estatic on the deal we made. I beleive that the TI subframe is about $450 US retail.


MITCH- Email me with your phone number or post it here for me.

Need to have a chat to you :)



**Ride it like you Stole it!**

Matt Porritt

99 YZ400F

Vist the Rubber Chicken Racing Online Shop

Discounts for ThumperTalk members.

Originally posted by Mitch from Oz:

Oh, one more thing.

Dont buy the KTM, does not compares interms of engine performance


I had a good long ride on a KTM400 on the trails that I ride every weekend, and boy is the suspension good, the WR really doesn't come close in that area. The KMT didn't have the power of the WR, but in the mud it was quicker because the power curver was better and didn't wheel spin as much.


RodH Canberra, Australia<A HREF="http://www.400thumpers.oz-au.com" TARGET=_blank>

400 Thumpers Australia</A>

2000 WR400F See Photo's and Modifications

Just a quick thought: If you think the dangling hot start is undesirable (duh!), invest in the Ty Davis handlebar hot start system. To mount this system, you end up plugging the stock air box outlet anyway.


didn't someone say that this years YZ426 rear subframe had been lowered by 1cm? would this come into the alignment & attachment problems?

That may be it... Maybe, the airfbox I received is for the 2000 model. I will need to clarify this...

Thanks Taffy


This air box design, what makes it so special, how does it differ than stock?

Hey Kevvie,

What makes it special is the following:

1. Velocity Stack. The standard unit (FROM CARB TO airbox) is a constant diameter all the way through. The new Velocity stacxk is "tappered" AND has velocity jets built into the stack to control "dead" airflow into the carb.

2. The airbox size/volume is larger. Thus, the "dead" air volume is larger. The dead air volume is what controls the air flow to the carb. Stable air flows more uniformaly than disturbed air.

Does any of that make sense.. :)

It does make sense Mitch. Now how the hell do I explain to my wife why I need the airbox too (and my pipe)?


What pipe are you currently running? Is ytour pipe a low/mid pipe or a mid/top pipe? Mine was a mid/top pipe and I was lacking severly in the bottom end. Due to the tappered nature of the velocity stack, my mow end was dramatically improved and my mid was also improved (although not as much). I already had alot ontop.

What the airbox did was improve the botto and mid and "smooth" out the whole power spectrum.

What excuse can you give your wife? Hmmmm, Since you did not come down under and you are waiting for her, maybe you could use the pipe as travelling buddy compensation. This is payment to you for dragging her along... :)

Mitch,I am presently using the stock pipe w/ insert removed. I am seriously looking at FMF Power Bomb w/ PC-IV/2 SA.

Today, my neighbor and I were riding at a local OHV park. Some kid was blasting around on his Honda CR-80. Someone complained of the noise. We had just come back from a typical Northeastern United States enduro loop (very tight, lots of rocks and roots). We were ready to go for our final run when the Conservation officer came upon us. He studied our bikes long and hard. He asked if we had spark arrestors, STOCK pipes and 2 stroke or 4 stroke. Dan's KTM MXC 360 has an FMF pipe. The Warden had Dan start up his bike and rev it up. He passed the test, I guess. I was not asked to start up the WR. I think the guy would have crapped his pants if he heard how loud it was.

I am waiting for FMF to unleash this new quiet cap for their VERY QUIET PC-IV/2 SA that has a noise output up to 104 dba.

I need to open my own shop (which I had planned) so I can get all this cool stuff you guys w/ the "Connections" get!

Hey Kevvie,

Maybe you can come and work for me. I am planning on opening a shop within the next 6 years. I already have it planned out. I have already picked my Service Manager and Sales Manager. SERIOUSLY. Both parties are very interested in moving to Australia and helping out.

I am waiting to see how my stocks go over the next 18 months. I will re-invest once the IPO stocks go really high and sit on the funds for the next 3/4 years. I will then move on the bike shop plan. I may have a few interested parties/friends who will be willing to denote funds and assist with the shop.

With the SuperMotard series starting (first race delayed 2 weeks) I am hoping to get some notoriety through my riding prowess. In addition, assisting a few magazines with writing articles. If that all comes through, then maybe get involved in testing of SM bikes. This would assist in getting the "name" that people will recognise.

Anyway, that is the low down. I would contact YAMAHA USA and speak to their tech guys or maybe contact White Brothers and ask to speak to Gary Jones in the R&D department and ask for his advice. I will give him a call tomorrow.


Hey Mitchy,

You WILL need a representative from the U.S. to translate some of our goofy slang...

I am serious about my shop too. It would be an accessory shop only, unless Cannondale gets their act together.

If you need help, I'll talk to the wife...???

There would be a central shop location is a trendy part of town. Williamstown for instance where alot of motorcyclists spend time on the weekends. Great Cafe's, restaurants, etc...

The central shop would deal with bike sales and would have a cafe located on the premesis. Thus, when a customer wants to talk about the bike over a coffee and appears to be a serious buyer, well, you offer them a coffee and a danish on the house.... For those who just want to hang out and drink coeefee and eat danishes and dougnuts, they will pay obviously.

Also, monthly rides for interested people as well as 2 clearance sales per year where demo models and such are auctioned to the hjighest bidder.

The real killer is the Satellite repair and parts stores. These will be located all over the Melbourne Region. These stores will be just parts and service/repair and not bike sales.



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