Harley Stage 1 Vs Stage 2 Vs Stage 3 Vs Stage 4: In-depth Explanation

Most Harley enthusiasts don’t like the stock shocks, mufflers, and other features. And there are plenty of brands that are offering better performance upgrades like installing slip-on mufflers, better air breathers, etc. in these fields. This is what you know as upgrades in various staging. 

The truth is there is no definitive guide to it. What someone calls a stage 2 upgrade, another one will call it to stage 1. Apart from minor opinion gaps, the basics are pretty much the same.

So, in this article, I will help you to differentiate among Harley stage 1 vs. stage 2 vs. stage 3. If you are looking for Harley stage kits explained in simple terms, this is it.

Harley Stage 1 2 3 4 Explained

harley davidson

To explain it broadly, it’s the gradual upgrade of your Harley Davidson to explore the full potential of it. Some upgrades will offer you more mileage and prevent bottoming-out. Your cost will increase at the same rate too. Gradual stage upgrade means increased cost too.

That’s being said, let’s dig into deep.

Harley Stage 1 Upgrades

All you do outside the motor is stage 1 improvements. When you think about efficient fuel management, replacing the old intake, ECU mapping, and exhaust – you are talking about stage 1 upgrades. You will notice massive performance improvement once you are just done with the above.

With those modifications mentioned above, your bike will breathe easily which in turn gives it increased power.

Sometimes, you might be wondering why your Harley is not sounding like it should do or what you here in the movie theater. Well, you need to upgrade the exhaust system. These are the most basic things you can do for your HD. You are just trying to achieve better gas mileage and exhaust gases out.

If the engine breathes well, your bike will perform better. So, it makes sense to have a muffler and air filter in this stage for the better airflow in and out. Besides, most Harley enthusiasts get it so make it louder too.

After every upgrade you do, you have to auto-tune it with the FP3 Fuelpak fuel management system. This alone offers you more speed, gas mileage, and many other features you never knew.

You need to be careful about these changes yourself. If you are still on the warranty period, talk to the dealer first. They won’t honor the warranty if you make any changes without letting them know.

With the extra charge, they will do these changes for you. But if the warranty period expired and you know what you are doing, you are welcome to make such replacements and upgrades.

Now, notice carefully.

Nothing involves doing any modifications to the motor engine or internal mechanical parts in this stage. You do need a better air cleaner, so a slip-on muffler from any reputed brand like Vance & Hines should do the trick. You can get an FP3 fuel management system from the same brand.

I have seen a lot of HD enthusiasts asking why Harley doesn’t implement these upgrades in their factory. Well, the reason is pretty simple. They have to abide by the environmental rules and regulations.

Even if you are living in California, you can’t do any such modifications I just talked about due to stringent environmental protection law. Check your local laws first before you make such upgrades.

Harley Stage 2 Upgrades

In stage 2, you do some minor changes in the motor like porting, chips, cams, etc. So, professional help is much appreciated. You do not want to mess with the engine tweaking it yourself unless you have previous experience doing so.

And the reason it’s called stage 2 because you should not be doing anything like getting a performance cam upgrade unless you have completed stage 1.

harley davidson engineSo, if you are wondering whether can you go straight to a stage 2 remap or not – the answer is NOT. You must complete stage 1 first. In fact, after the completion of stage 1, you should run the bike for at least 1 or 2 years to understand whether you need increased HP or TP.

And yes, you guessed it right – in this stage we will talk about cams. You may know it as lifters too. Picking up the right one will completely change the way your bike behaves. It gives more power everywhere and most importantly, it’s EPA compliant!

Installing cams give your bike increased horsepower (HP) or torque or both if you want. The increased HP maybe 20% to 25% than the stock and the same goes for the TP too. This is basically fine-tuning your HD for the smooth performance.

Important Advice
When you think about cams upgrade, just keep in mind that less is more. Big and fat cams will make your bike disappointing. You won’t have a smooth ride. Get the cams(either HP/TP/both) that say perfect for low-mid range so that you can actually ride your bike.

We are talking about huge money spending here. The dealer may charge your $500+. Total cost (including the cost of the cams) will be more or less $1,500. And if you complete the stage 2 successfully, you won’t be disappointed!

Harley Stage 3 (The Big Bore Kit)

Well, stage 3 is what you have done for stage 2 plus the headwork. If you want even more power than what you got from stage 2, you may think about it. But let me tell you the disappointing part first.

Many Harley owners skip stage 3 and go directly to stage 4 because they think stage 3 upgrades simply don’ worth it. Don’t forget, it will cost you several thousand (more or less $2K) including labor charges.

But why should you do this? What you will get really out of it?harley engine

Such upgrades will increase the displacement of your engine. Increased displacement results in an increased output of power everywhere. In any stage you make any changes, you must tune it using any auto-toner. That’s why having a Vance & Hines fuelpak fuel management system is always a good idea.

Imagine you want to pass a semi on the highway easily or you want to ride your bike with someone heavier on the passenger seat without noticing anything, these upgrades will help you to achieve this. You will be comfortable in every riding situation you encounter.

All you need is a big bore kit that includes pistons, a larger bore bolt-on cylinder, and other stuff to make the change. And no machining is required to do so unless you go for the bigger size cylinder bore which is overkill to me.

So far I have tried to differentiate among Harley stage 1 vs. stage 2 vs. stage 3. I hope you got the main points. 

Harley Stage 4

Along with larger throttle body and injectors, you will be needing more headwork than what you have done in stage 3.

If you are a power addict, this stage is for you. Stage 4 bikes are pretty rare on the roads because such upgrades give you huge power but your bike will lose the rideability. And don’t forget, it will cost you serious money for far less improvement than what you have achieved in stage 3. 


From the above discussion, you might be wondering where does it end? Seriously it does not. Besides, what you have done for stage 3 today for your HD will be obsolete in a few years when a stage 2 upgrade will give more power and performance. So, analyzing your need practically is important!

6 thoughts on “Harley Stage 1 Vs Stage 2 Vs Stage 3 Vs Stage 4: In-depth Explanation”

  1. I had a stage 1 done on my 2015 wide glide, more free flowing airbox, and V&H’s short
    shots with the ecm to put more gazola into the engine. what a great change! throatier and more beef, yup the old lady from Wendy’s would like this she was always bitchin “where’s
    the beef?” in my wide glide, woman. . . running stock was lucky to get a bit over 50, after she went thru the change, totally awsum

  2. Thanks for the info on the upgrades. I wasn’t sure which way to go with it. The information you provided and the explainations were extremely helpful. Made my decision on what I’m going to do, thanks for everything. Let you know how it works out for me.

  3. Leave it stock an with money buy FUEL an trip out ,if you want to fly buy a speed bike you can’t stop these big heavy bikes on 2″ of rubber on road with your fat friend in an emergency you will crash no more riding for you SUCKERS when your trade them in the dealer with buy them right away because it stock easy sell for them go trade your Frankenstein in raped ,they are cruisers you the bike come from the factory perfect an then when they are bought they start chopping them up what a waste, after ride for a while with that racket of noise your cool show off

  4. I have a 2013 Tri-Glide with a 103. I need more power, more noise and better rear suspension. The motor is stock except for Vance and Hines slip ons. Any advise on these matters would be highly appreciated.

  5. So what stage is best for normal everyday riding but wanting more power at lower rpm for when needed / wanted? A stage 2 or 3?

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