400ex mods....

[dirtmerchant42]

my friend and i are looking for some more power after riding our friends yfz450!
i have an 03 n he has an 06 400ex

intake, exhaust, n jet are in mind

for exhaust we dont want one thats too loud, one friend has an hmf on his 400ex and i dont want mine to be that loud

what kind of intake do yall recommend?

thanks

[trx400EXtreme]

for a filter..... i would go with a K&N w/ outerwear and no air box lid. IMO that sthe best "bang for your buck". for a pipe..... it's really hard to say. the HMF does give you quite a bit of power, and they make a quiet core for it. it only costs 20 bucks.

[dirtmerchant42]

how do you like your white bros?

[trx400EXtreme]

I love my R4, but it is very loud. actually my cousin has an HMF and they sound pretty close to the same. plus, the R4 is discontinued so they are harder to find. personally i'm a fan of all white bros. pipes. you could look into the e series. i don't know exactly how loud they are but there is tons of people on here that could tell you.

[XXXRACER165]

I like my WB too but I recomend LRD.

[twain68]

You could also put on a aftermarket rev box and a monster coil.

[twain68]

The DMC Quiet system is the perfect choice for the track or the trail. Designed to improve the spread of horsepower, torque and acceleration while keeping sound down to strict USFS sound requirements. Features include a completely re-packable extruded alloy silencer with premium packing material, T-304 Stainless steel mid-pipe, AMA/FIM approved end-cap, removable U.S. Forestry approved spark arrestor and DMC S.O.S. (Save Our Sport) quiet insert. The Pro Quiet pipes maximize performance as a full system, but can also be purchased individually as a slip-on muffler or head-pipe. Purpose built to conform to all off road noise regulated applications, our test results show an output less than 96 decibels.

[Kennethyfz450]

Almost any exhaust you buy for the 400 will give you 1-2 hp gain over stock. I personally like the e-series ; however, if you do any jumping you will put a nice dent in the can. Some people even experience cracking.

My second favorite is LRD.


I like those two the best due to the sound. A drop in filter (k&N , Uni, Twin Air, etc) with the air box lid off should help you gain more ponies if you dial the 400ex in correctly.

[tdmopar59]

i am the one who has the 2006... i was just wondering... as far as exhaust goes.. if it fits the 03 it will mine too right?? also what do ya'll think of yoshimura?

[Mercedes]

I got an 06' with K&N, outerwaer(NO lid depending on condition), a Curtis Sparks full exaust and timing advance chip.
I got my ride stock and putt all this on at the same time. The power upgrade is crazy and trottle responce as well(thanks to the timing chip).
Curtis Sparks is not crazy loud, but has a nice pop to it.

[tdmopar59]

where did u get the timing chip?? what brand is it and all that?? i like curtis sparks... its just expensive

[Mercedes]

You could get the chip right from Curtis Sparks or on Ebay, its not expensive at all, dont remember exactly but 50$ shipped I believe.

[tdmopar59]

hmm... i'll look into those.... does anyone use the yoshimura exhaust?? i have heard good things but only from yamaha guys...

[trx400EXtreme]

my cousin has a yoshi on his 400 and it's not too loud compared to ohers.

[08400EX]

Originally posted by tdmopar59
hmm... i'll look into those.... does anyone use the yoshimura exhaust?? i have heard good things but only from yamaha guys...

You can't go wrong with Yoshi, those guys have been around a long time and know a thing or two about making exhaust systems.

I just installed my RS-3 Carbon Full System and the quality of the components is second to none.

[tdmopar59]

well at this current point in time i think i will be going with yoshimura rs-3 full system... my only question is... whats the difference as far as getting a slip on vs. the full kit??? is it worth the extra cash? right now my quad is stock.. i plan on doing intake exhaust and jetting it... naturally as time goes on the mods will get more extreme though....

[08400EX]

Originally posted by tdmopar59
well at this current point in time i think i will be going with yoshimura rs-3 full system... my only question is... whats the difference as far as getting a slip on vs. the full kit??? is it worth the extra cash? right now my quad is stock.. i plan on doing intake exhaust and jetting it... naturally as time goes on the mods will get more extreme though....

If you plan to do more mods down the road get the full system.

If you know FOR SURE you are gonna be satisfied with just a slip on and filter mods, get the slip on.

Keep in mind it will be almost impossible to find the rest of the matching full system later on if you just get the slip on now.

[tdmopar59]

well... looks like i will be saving my pennies..... i think im gonna get the regular stainless system or whatever though.. the carbon fiber is sick just not worth the extra cash to me... any ideas where the best prices would be??

[08400EX]

FYI, if you do plan to get the slip on, there is a killer deal on Ebay right now, Brand New $220 BIN, $10 ship Item 150214018073

If you want the full system, Leesons Motors has a Stainless Full system on Ebay with a $545 BIN w/free shipping, but it also has the Best Offer option. Make them an offer of $400-420 with the free shipping. I bet they will accept it. Item 190128529064

IF you want the Carbon Fiber version Leesons also has one with a $595 BIN and free shipping, it also has the best offer option. Offer them $460 with free shipping , I know they will take it. Item 190128530130

[tdmopar59]

well i think i found an even better deal!!! i was messing around ebay and i found a vendor site where i can get the full kit for 384! now i just need the cash!:devil: lol well maybe towards the end of the month or something...

[tdmopar59]

i think the only way i could possibly get anything cheaper is if i find it used... which is gonna be a challenge and a half!

[hondaking52]

ya the sparks ignition advance KEY.. not chip, is a good way to get some good power and is a breeze to put in,they actually show u on here how to install it,and with a pipe and filter u should be good..

[07trx400ex]

tdmopar please tell me where you can get the full yosh carb rs-3 for 384 VERY INTERESTED I need an exhaust especcially for that price

[shockwave95]

Originally posted by 08400EX
FYI, if you do plan to get the slip on, there is a killer deal on Ebay right now, Brand New $220 BIN, $10 ship Item 150214018073

If you want the full system, Leesons Motors has a Stainless Full system on Ebay with a $545 BIN w/free shipping, but it also has the Best Offer option. Make them an offer of $400-420 with the free shipping. I bet they will accept it. Item 190128529064

IF you want the Carbon Fiber version Leesons also has one with a $595 BIN and free shipping, it also has the best offer option. Offer them $460 with free shipping , I know they will take it. Item 190128530130

Thaks for the tips. I might get a new Yosh for pipe

[08400EX]

Originally posted by shockwave95
Thaks for the tips. I might get a new Yosh for pipe


You are welcome! There are many good pipes out there, but I do know for sure you won't be disapointed with the Yosi.

[tdmopar59]

www.motoxoutlet.com they sell on ebay as well.... but it seems like with shipping its the same as 08400ex's deal....

[07trx400ex]

Thanks, man. The RS-3 Carbon Fiber Full System is 454 sale price, but the slip on is 334.

[08400EX]

Yeah I talked to those guys before I got my Yoshi Carbon. The best they would do is $459 plus $25 shipping. Plus they are on the west coast (5-6 days shipping time to me) I got mine from Leesons for $459 shipped and had it in 2 days since they are in WV.

That is a smoking deal on the stainless full system at $384, but when you add $25 shipping to it, it is not as good a deal as what I know you can get at Lessons. AND , if you are on the east coast you will have it a LOT faster.

[tdmopar59]

08400ex i think i will use the same method you used... i just gotta save some cash up... it will prolly take about a month.. because well... other bills LOL... but i sure am excited to start modding this thing!!

[07trx400ex]

i found a hmf ballance edition(full) on ebay for 450 plus free jet kit, shipping, and any color you want so i think I will try that when ever I have enough time.

[07trx400ex]

I forget to mention it comes with a quiet core, and spark arrestor so it is USFS approved. I do not really think the trm will work but I will be finding out here in the next month but I liked the look of it and especially like the carbon fiber and that it says Ballance on the side and it should be "adequate" performance since it is coming from hmf.

[250exkid]

whats a monster coil do for you? benificial for a stock motor?

[07trx400ex]

It is supposed to increase spark which gives a more complete burn of fuel, that should give you more power and the power should be felt quicker.

Look up amrracing.com
It should be beneficial for any motor but I have never used one on my quad.