I know that exhaust questions have been played out on here, but I've gotta find some things out. I have looked at the Duncan Double-Barrel, Curtis Sparks X-6, or the White Brothers E-Series Pro-meg full systems for my 400EX. Here are the things I'd like to know:

1. Which holds up the best to MX abuse?
2. Which will work on mildly modified as well as heavily modified motors?
3. Which gives the best power increase all throughout the powerband?
4. Are there any dyno charts of these systems?

Any help is appreciated. Thanks.

 

I would go with the Sparks. The X-6 is for any kind of modifed motors. Mild to as much you can get out of your motor. The Sparks X-4 won the shootout in ATV Sport, and the X-6 is even better so it would add the most power with a built motor. I`m not sure if they still have the dyno`s on atvnews.com or not. The X-4 beat the White Brothers Pro Meg and the Duncan complete exhaust. What do you have done to your motor or plan on having done? Check out Sparksracing.com.

 

I have a stock-bore 11:1 compression piston, and an XR400 cam, plus a Uni filter, open airbox, and Dynojet kit. I eventually plan to get a 416 or 440 from somewhere like TC, Duncan, or Sparks.

 

I say you go for the sparks X-6 jsut bc the x-4 had the best power in the shoot-outs

 

The Sparks X-6 exhaust looks like the best out of the three. How does the X-6 stand up to motocross?

 

i had the x-4 on my 300ex, the 1994 one. It added great power, was a strong built pipe. But very loud!

I wouldn't get the x-6 unless your motor is built.

The 300ex one goes for 282-300 for the x-4 300-350 x-5 and 350-405 x-6

i'm sure it would work 400-416 for the x-5 416-426 and 426-465 for the x-6

Call sparks and see how it works. I know thats how they list the 300ex ones.

 

Curtis Sparks only makes two exhaust systems for the 400ex. The X-4, which is for stock engines and the X-6 which is for built engines. Your engine is not stock. So you want the X-6. Call Sparksracing or email them. Sparksracing.com

 

Okay. I got out my June 2001 issue of ATVsport magazine. This is the issue that tests 17 different exhausts for the 400EX. I found that the Curtis Sparks X-4 and White Brothers E-Series Pro-Meg full system were the two best out of all tested.

Here's what I found:

The Sparks had a 1.9 HP increase over stock at peak, while the White Brothers had a 1.7 HP increase. From 15 to 30 mph, the two systems were similar. Right at 30 mph up to 40 mph, the Sparks unit seemed to dip a little, while the White Brothers did not. At 40 and up, the two systems seemed similar.

You can look at the dyno results HERE.
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What I would like to know is:

1. Which would work better with a lightly modified motor, then a heavily modified motor later?
2. Which looks like it gives the better power increase?
3. Which would you buy? Why?


Thanks very much to you that reply and help.

 

Anyone?

 

I would half to go with the X-6. It is made for modifed engines. If you have little mods right now and big engine mods later it won`t matter, it`s made for that. Curtis Sparks had a 505 kit on his site at one time that used the X-6 in the package. Not only does it make more power, but it is also lighter than a White Brothers. I would go with the Sparks. I would go with a Sparks 416, 440, or any motor mods he made. I think he is one of the best, if not the best engine builder. His 250 powervalve is in the lead in the pro points race right now with Jones. SPARKS