I have been trying to research what slip on exhausts people are using on the 400 ex and haven't seen to many different ones on here. I want to go with a slip on I think and would like to gain mainly mid range power. I will probably also buy a filter and switch jets if I need to. Any suggestions to get me pointed in the right direction for what I need would be appreciated.

 

I guess it all depends on how much you want to spend. There are a lot of good performace exhaust systems (full system including slip on exhaust plus headers) as well as slip on exhausts out there for the 400EX. You could possibly gain 2-3 horsepower with just a slip on or up to 7 as some makers claim with a full system. I find that up to 5 more horsepower is a believable gain with a full system. But it sounds like you want just a slip on exhaust. Right now on my '99 400EX I am running a full system White Brothers E-Series exhaust that added a very noticable power gain over stock throughout the entire rpm range, so I am inclined to lead you towards an exhaust from WB's. If I were you I would hear from multiple people before I made up my mind on which pipe to go with.

As for re-jetting, I don't think that it would be as necessary to do with instalilng just a slip-on as it would be for a complete system, though it wouldn't hurt any (infact it would probably help it a bit).

Here is a list of some exhaust makers just off the top of my head for you to look at. I am sure that most riders would find these companies to be reputible.

White Brothers, LRD, HMF, Yoshimura, Curtis Sparks, FMF, DG, Trinity Racing...etc. (no particular order)

Also ebay is a great spot to find varying brands and prices of exhuasts, I am sure others will tell you other good spots.

 

HMF slip-on, UNI filter, 155 main and a 42 pilot jet and you're golden. All for roughly $250 if you look around awhile.

 

My neighbor had a wb e-series on his 440 ex for a while, but switched that with a big gun because he didn't like the way the wb sounded - after a certain rpm it sounded kinda like a lawn mower for some reason, but the big gun kicks @$$, the power gain was a little better than the wb, and the big gun has a more powerful sound. It's louder than hell though, so if sound is an issue for you then steer clear of big gun, even the quiet series is pretty damn loud.

 

HMF slip-on from E-Bay. About $240 with correct jetting, new filter, and hardware!

 

Do you have to change your jetting when you install a slip-on? I have been reading a lot about the LRD slip-ons, has anyone had any experience with these?

 

I would say that if you are going to change the way your quad breathes by adding a freer flowing exhaust that you would most certainly have to change the jetting. because it would be getting more air than it was originally, thus it would be running lean( i believe). if you buy a tunable exhaust you will notice that if you run it wide open(the exhaust) it will backfire profusely. If you run it with mininmal amount of discs it sounds stuffed up and it will not run. i would have it re- jetted. otherwise you will not be happy.

 

there are only a few quads that can get a slip on exhaust without being rejetted, and the 400ex is not one of them. HMF even claimed that my warrior didn't need to be rejetted with the slip on but when I installed it the thing was lean and needed to be rejetted anyways. I think that most of the time HMF includes the recommended main jet with the kit so you won't have a hard time finding the right one, but a rejet will be required in most cases, unless your quad is jetted rich to begin with

 

I decided to go with the LRD Pro 4 Series exhaust along with a K&N filter and a precharger for the real dusty areas. The stock main jet was a 148 and I replaced it with a 152 and did not adjust the needle.

Would it be a good idea to move the clip on my needle down one spot to richen it up in the mid range or not? I am going to hit the sand at Christmas Valley this weekend and will let everyone know how it performs.....Thanks for all the feedback

 

dirt wheels pipe shoot out the ct racing one had the most power gain but the white bros e-series won and was like only point sumthin less power than the ct and was a little quieter but if u wanted a loud one get the e-series and i can tell u how to make it alot louder