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Discussion Starter · #1 ·
What's up y'all? I recently purchased a 2012 ltz400 at a decent price I plan to build it up. It came with pro armor nerf bars and pro taper fat bars, besides that it's pretty much bone stock. I ride in NH, MA, and RI.

Ive been researching different mods people have been doing like throwing on an ltr450 throttle body and injectors. One mod I can't clarify is exhaust systems on these fuel injected models. I've been looking for different exhaust systems and what people have been doing with tuning and I can't figure out what is the most successful exhaust set up for these fuel injected models? What brand has the best reviews? HMF? Yoshimura? Big gun? what's the best bang for my buck? I've read people using tuners you program through the computer and ones that have preset settings you just change on the fly.

This is my first fuel injected quad, I'm used to my 07z400 (running a yoshi) and I've read horror stories online people throwing on a simple slip on and ruin their quads without tuning them. I primarily am looking for performance and could care less if it sounds like cats fighting for territory. What are your guys opinions/experiences?

P.s. This is my first post, so go easy on me ladies and gents
 

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Welcome to the site!

When it comes to exhaust, let me start by saying that all the full exhausts are going to help, and all will require a tuner. One common misconception with efi is that it will tune itself. These do not. They are pre programmed and run on a map. Not only that, but thanks to epa regulations, they don't come tuned for power, they come tuned for clean emissions.

Next, exhaust threads used to be pretty heated topics around here. Most guys would insist that the one they bought was best, and provide no actual data as to why. Then there was the dirt wheels article from way back in the day, where they did a dyno shoot out. Unfortunately, they didn't bother to tune each pipe in, so it wasn't accurate. That's also very old info, and no longer relevant.


If horsepower is what you are looking for, then Barker, Empire, and Yoshimura are the best ones I've run. They are the best ones to go with if you think you will ever get into heavier engine mods like big bore kits and what not.

I can get you a Barker or an Empire industries pipe at a discount. I know I can do a package deal with the Barker and a Power Commander 5 programmer that is already tuned and ready to go. I'd have to check and see if Empire can do that. I haven't crossed that bridge yet. If not, then you would have to take it to a dyno to get it dyno tuned.

Barker on my own machine







Not the greatest picture, but here you can see the Empire Industries exhaust on Blackkawi's KFX



Both of those pipes come with several color options also. I have run both on my own machine back to back, and it was really hard to pick a winner. It would take a real dyno to tell them apart.



I personally like the Power Commander PC5 for a programmer and most of my experience is with those. Their system is easy to tune, with downloadable maps that you can get off their website, or even from other riders with similar mods. The other brands of programmers that use buttons on the box to get tuned in are not nearly as accurate. Power Commander also has an autotune available as an add on accessory that uses an oxygen sensor to get it's map in the ball park.


The EFI Z is no slouch, but it does come with some extra challenges. The stock throttle body is too small to get serious with, and the LTR throttle body is adaptable, but for a larger build, even that would fall short. The next one is I don't believe there is a way around the stock 9100 rpm rev limit unless you can switch over to an LTR ECU and get a hold of a CRBM. This kind of work isn't for everyone.




Here is a link you may find interesting also. http://www.suzukicentral.com/forums/137-cfm-motorsports/134274-efi-head-porn.html
 

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There is definitely a lot good information in this post. It's a great debate which model was better; carb vs EFI, but in my opinion I wouldn't trade my EFI for a carb any day (Just my opinion). Like CFM said, a full exhaust will provide much more gain over a slip on any day.

This is where I may catch an ear full but I will speak my opinion. The stock model EFI maps came pre-programmed from the factory relatively rich. The reason I say this is because all of the maps that can be downloaded from the Power Commander website actually subtract more fuel then they do by adding it. I believe the only map that adds fuel is the Pro Circuit slip on/open lid map. All the rest for example, Yoshimura, FMF, Pro Circuit maps subtract fuel. After I purchased my CT racing exhaust 4 years ago, I ran the quad without a programmer and a lid for many months and honestly, it ran just fine. I kept an eye on the plug and did many plug chops to make sure it wasn't running lean but it seemed to perform well. It was later I decided to buy a fuel programmer. The truth is, with or without the programmer, I couldn't tell or feel any difference in the performance of the engine back when the engine was stock. Whether or not this is scientifically proven right or wrong, I'm just providing you with my experience in dealing with the EFI system.

In the end I am happy that I purchased a fuel controller because once I started modding my engine and becoming more comfortable with rebuilding the top end, it has been important in helping my with my 450 big bore kit. I'm not sure if they still make the 2 Bros Juicebox Pro or not but I chose this over the PC5 because the tuning software works just like a PC5 and that this system has the capability of storing 10 maps and the ability to switch them on the fly without needing a laptop PLUS the Juicebox was also compatible with PC3 and PC5 maps too! Unfortunately the Juicebox Pro unlike the the PC5 does not have the capability to run an 02 sensor like an Autotune system but so far have not needed the ability to do so.
 

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Discussion Starter · #4 ·
Well I've been doing a lot of thinking and research, I'm thinking of going with a full yoshimura system just becaus I had a gsxr600 that loved it. My only experience with pro circuit is on my 07 crf250r, I bought a used but great condition T4 titanium exhaust, great power but used a lot of fuel.

As for a programmer Im not sure on whether to go with 2 brother juice box or a pc5. I'm learned the juice box also works with pc5 software and is cheaper, but you're right it doesn't have what dyno jet has with the auto tune for the o2 sensor which again is extra $$$ on top of the pc5 of you get it. is the auto tune really necessary or is it something used to a fine tune in

Ive heard of barker and empire, a buddy of mine runs a barker on his quad too, he keeps telling me to also stay away from fmf and the whole power bomb header thing they got, it worked great for the older models. I've heard great reviews from HMF, I don't know if Suzuki or any z owners use HMF, my GNCC buddy who races a 09 yfz450 loves it but I know Yamaha engines like HMF. He keeps telling me to give it a try, they have a whole system with a programmer that is preset for my z.... Again i don't know if I want to stray away from yoshi. It's a lot of money and I'd like to spend it once
 

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after reading all this I'm super glad i picked the full yoshimura rs2. The dealership where i purchased my 2014 z kept pushing me to get a hmf instead
 

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Discussion Starter · #7 ·
I got a problem with my PC5 now..... The fuel injector harness' are different but the TPS sensor harness went like cake... You can see from the pictures that the bottom of the harness that came with the PC5 is flat on the bottom and looks like it has groves it slides in and the location of the 2 pins are in a different position than the stock one. Idk what to do now, I think I saw a post that someone had the same issue while they where hooking up the same exact exhaust and commander.... and I can't find it anywhere now

I'd like to get someone's help with the issue I mean it's a 2012 but the item I bought from eBay said 09-10 ltz400, did Suzuki really change the fuel injector harness? I'm about to send it back and get a pim2
 

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I have a flat spot with my 2014 z at around 10% throttle. Full Yoshi rs2, powerlid, and pcv with a Dyno tune. Tuner said he couldn’t get the spot out. Has anybody else had this problem with the efi. Ran perfect before I started modding it. I think it has to do with the “open” air box. Haven’t found anybody else with my issue and is very frustrating.
 
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