We tested the Dr. D

My buddy and I both have 2005 YZ 4-fiddy's and have been checking out some mod options. Our local dealer was nice enough to let us test the Dr. D exhaust system and told us if we didn't like it that he would put it on his own bike. He was sure we would be more than impressed. Make note that our stock bikes have always been dead even.

We installed the pipe on my bike and headed for the sand dunes. We drag raced several times and stayed dead even. No difference. We then went to choke cherry hill for some climbing. On the first run his stocker out climbed me (me on both bikes). He is running an M5B and I had a Pirrelli MT32. We drag raced up the hill and stayed pretty even other than he went higher on his stocker.

We went back to the truck and traded back rims/tires to see if the tires were making the difference. Same results. The Dr. D did not make any difference. None!

I'm not here to bash any one brand, but I'm sure glad that I didn't spend 500 bones on this thing. Does anyone know if the pipe changed from 04 to 05? Maybe we had the 04 version??? What really works out there?

I have read several threads of people liking this pipe, but has anyone really done a test like this? I honestly felt like my bike was a little crisper before we started racing/climbing. Does the different sound just make it seem that way?

I'm confused.

I don't doubt your results.

I think many people are fooled by noise.

Good job!

BTW I hear an 03 CDI control box makes a big difference on an 05 450.

I don't doubt your results.

I think many people are fooled by noise.

Good job!

BTW I hear an 03 CDI control box makes a big difference on an 05 450.


Are there any dangers associated with the box swap from a reliability standpoint?

I think people in general don't give Yamaha enough credit for the fine job they have done with the stock exhaust. Unless you need a spark arrestor, there's really not many reasons for swapping it.....even then, you can get an insert and save a bunch of cash.....Great job, Yamaha!!

Should it not need some jettign to get the improvements that may be due from it? The bike with it fitted may have been running a bit lean with it. If you dont put the gas in, it wont make power, simple.

Not saying it will make anymore, but try going one size up on the main, and see if it helps.

The Dr. D pipe along with a few others claim to not need jetting adjustments.

If you want a pipe that helps the 05 rev better try the procircuit Ti-4 slip on.

So you have an 05 with the Ti4 on it? Is it the 14 or 17 inch version?

I don't know where Dr D claims to gain power but it sounds like this was pretty much a top end test. Drag racing and hill climbs and such. Maybe it is supposed to have more low end. It would be pretty hard to measure on the track though. In all likelyhood what you have found is correct. Your average dude is probably wasting money on a pipe in this case.

I really doubt that "drag racing" and hill climbing is an adequate enough test for a MX bike and MX pipe. . . :cry:

Why not?

If the pipe makes more horsepower it the drag race would show it.

For 500 bucks you should see some increase.

I think pipes are just bling.

But since I have never tried an aftermarket pipe my opinion isn't worth much.

hmmm you know I dont think I know whether it is a 14 or a 17" pipe. I'll measure it later this evening.

The pipe was one of several things I tried coaxing some acceleration out of mine. It definitely makes more power than the factory pipe at mid to wot.

No, that's where ya'll are totaly wrong. Dont add a Dr. D for topend. The Dr. D is specifically designed for racing mx/sx. I have also rode the bike with a Dr. D. The bike pulls harder on bottom, to mid. If your looking for top, I might try the fmf.

Why is a a drag race or hill climb to a 100% accurate test? Becuase most aftermarket pipes only increase the power in a specific RPM range and it commonly comes with a trade off in some other range. You can acoustically tune a pipe to a certian rpm range but that well lessen the efficiency somewhere else. If you slap on a pipe that increases power in the lower range you could likely lose some on top. That is assuming the stock pipe is not overly restrictive. Replacing a WR pipe with a YZ pipe would probably increase power across the entire RPM range.

Soooo, maybe the Dr D pipe is designed to gain on the bottom at a loss on top. I saw an article last year that did dyno runs for every pipe I have heard of on the YZ450F and some did just that.

I would say you should not spend money on making more power but on making it easier to use what you have. Suspension, brakes, controls, yada yada yada.....

Or, I have seen a nitros kit for dirt bikes. I DARE ya!!

I agree that drag racing and hill climbing may not be the ultimate test, but a $500 investment should make a difference in both of those areas. Power is power. We started from a dead stop, we also rolled them on from 2nd, 3rd, and 4th. Still no difference. We also "cat and mouse" on tight turning whooped out sand trails and found no advantage. We did NOT go to the track.

I bought a $179 gold series for my CR 500 years back and couldn't believe all the extra power. I've also piped several snowmobiles in the past and have had very noticable results. I guess that's what I expected. What I didn't expect was virtually no difference.

Unlike the 2-srokes, maybe the stock thumpers are tuned closer to the maximum performance level.

If you can't notice a difference riding than why buy it?

I think you are lucky to have a dealer that will let you try out aftermarket items at no charge. It would have cost me 500 bucks to find out.

I do see your point but getting gains accross the entire power band just can't happen. With the older CR500 the stock pipe was probably pretty lacking. I think when you mentioned that the factories are probably already tuning them pretty well you are most likely correct. Even the best pipes only give maybe 2 or 3 HP at certain RPM ranges. You probably will not notice it in a drag race but "maybe" it would help just enough in some area to make it easier to clear jumps with a short run up.

I do have to agree with you when you say for 500 clams you expect $500 worth of improvement.

Come on, you know you want the nitros kit!!

Typically, it seems like aftermarket accessories make the biggest difference on brand new models. When a manufacturer does a total redesign, they may not have time to optimize every component of the bike. By the 3rd year, though, they have it pretty wired.

For instance, the YZ450 was new in 2003. I put a Jardine exhaust on it. I drag raced some stock 450s and mine revved farther and had a bit more top end than they did. $700 worth? Probably not. But it really helped me with the issues I was having with the 4 speed tranny.

Yamaha improved the YZ450 in 2004. And even more in 2005. There probably aren't many bolt-on gains left to be had.

There's always a trade off when dealing with after market exhausts. Bottom to mid, top to bottom, fit and finish, sound, etc. It's up to the individual to decide how much they want to pay, and how much of an increase in performance they'd expect from it. I have ridden (owned) a yzf 426 and 450, and a crf 450, and tried stock, Dubach units on all of them, an FMF on the CRF, and finally a Jemco. In my opinion, you may give up a little in the noise department, but the all around gains (and it's dyno proven!) you attain from a Jemco exhaust are the most performance to price bang-for-your-buck you'll ever get. You can get an entire system that absolutely rocks any $500 system out there for under $300. Go figure. :cry:

The funny thing is that my Yamaha dealer told me many of the guys who bought 05 YZ's are trying to make them run like the 03's.

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