Y
Depending on why you "have to" jump a long distance, you've got a few options. The deciding factor between these is mainly how quickly you need to be able to do it, and what you need to take with you.
As others have mentioned, Engineers are one way to boost your range. I definitely recommend checking them out, as they can indeed help tweak your ship components to boost your range beyond the ship's standard capabilities by 50% or more. However, each Engineering modification is a random roll. So, they're not exactly the most reliable solution. Additionally, they require a bit of grinding to unlock - and more to get the materials for each upgrade attempt.
One answer here suggests using FSD Synthesis. This is an option, but it's a rather cumbersome process that more than likely will cost you more time than its worth in the end. This is because you have to invest prep time in grinding for materials, and you also have to plot each boosted jump individually by hand. If you try to use FSD Synthesis constantly, to make up for low jump range on a long trip, you'll likely end up spending more time doing FSD Synthesis work than you would otherwise have needed to just make the extra jumps.
FSD synthesis is really better saved for situations where you find yourself in a really thin star field, and/or out of range of the next refueling opportunity. Flying to Altum Sagittarii Prime or wandering carelessly through a field of Brown Dwarves are good use cases for this.
Another option is to simply upgrade to a more capable ship. Just a step up (in terms of cost and game progression) from the Type-6 is the Asp Explorer. And that's the second-best ship in the game, in terms of maximum possible jump range. It's also widely regarded as the best multipurpose ship overall.
Still, there's a lot you can do with the Type-6 you have now. And, no matter what ship you fly, there's really no good substitute for a strong baseline build. Here, I'll cover how you can get your ship better optimized for jump range in general. Then, I'll address the particular needs you've expressed for your ship. At the end you'll have a ship that's reasonably similar to your original build, but with a substantial increase in jump range and a couple new features as well.
General Tips for Optimizing Jump Range
1. Remove everything that's not absolutely essential.
Depending on your play style, this can include otherwise-common things like:
Weapons
Shields
Scanners
SRVs
There are some components which the game considers "massless" though. So, it's generally easy to keep these without impacting your jump range much:
Fuel Scoops
Auto Field Maintenance Units
Planetary Approach Suites
(Technically, empty Cargo Racks and Fuel Tanks have zero mass. But they're not of much use in that state.)
However, be aware that even massless parts may have an indirect impact on your jump range. For example, their power requirements might force you to fit a heavier Power Plant. Watch out for this, and balance appropriately as needed.
2. Get the biggest, A-rated FSD you can fit.
This is what gets you where you're going. Even if you stripped out all the furniture and spare bulkheads (not that you could), your Type-6 Transporter won't get far on a 2E FSD. For the Type-6, the best you can get is 4A - and frankly, anything less in that ship would be uncivilized.
3. D-rate and under-size all remaining parts that have mass.
The D-rated components are the lightest components of their type and size. And some module slots will accept parts that are smaller than the slot size.
You can't get rid of your Core Internals, but you can reduce their impact on your jump range by fitting the smallest, D-rated part that will go in each slot and still keep you running. Even the massive Anaconda can be made to fly with a 1D Power Distributor and 2D Power Plant.
One thing that most people probably don't think about changing, which also can help your jump range, is the Fuel Tank. Carry just enough fuel for a single maximum-range jump, and that's a lot less mass that your FSD has to push around each time.
The New Coriolis
The Coriolis site you linked is no longer being maintained. A fork has been made by the Elite Dangerous Community Developers at https://coriolis.edcd.io. I do highly recommend using that site for concept-building all your ships before you actually buy parts.
The maximum range for a ship, as displayed on Coriolis, is an "absolute maximum possible" range without any regard for mission requirements or general ship usability. As such, achieving it requires that you follow all of the above exactly as stated without adding anything else on.
Here is a link to such a build for the Type-6. It achieves the 33 Ly jump range, but literally can do nothing more than get you (the pilot, alone, without cargo) from point A to point B. And you'll be lucky if you can jump 50 Ly without having to stop for fuel (either scooping from a star or landing at a station). Oh, you'll also want to mind that power management - don't try using the AFMU in Supercruise.
Also, even if your ship build matches what's on Coriolis perfectly, you'll probably still never (or very rarely) see the jump range listed as maximum on that site. That's because that stat also takes into account a very dry fuel tank - only enough for one maximum-fuel-use jump. Even though you may run into that scenario sometimes, it's not something your route plotter plans for. The route plotter always assumes you're jumping on a full tank. So, it's better to go by the "full tank" range. Also consider the "laden" range, if you're going to carry cargo.
After Jump Range, Add Usability
Oh, you actually wanted to do more than just fly around space all by your lonesome, two jumps at a time, and never have a substantial income? Yeah, you're gonna have to give up some jump range for that.
First thing to bump up is gonna be your Fuel Tank. Seriously, what were you thinking when you put a size-2 tank on a T6? Bump the Core Internal tank up as much as it can go. Maybe even consider adding a spare in Optional Internals - it'll eat up your per-jump range, but you'll get much farther on a single fill.
Next, beef up that power plant a bit. Go for the smallest, A-rated plant you can live with. This helps with heat efficiency so you don't have to worry about getting cooked too much while you fuel scoop.
Third, if you want to boost, you're gonna need a bigger Power Distributor. Coriolis helps give you an idea of what size you can go down to and still boost. Just keep in mind to stick with D-rated where you can. Especially for Power Distributors, a D-rated part in any size will be lighter than anything in the next size down except D. (For some other modules, the balance is slightly different but D-rated is always the lightest for a given size.)
Then, fit the Optional Internals and Hardpoints with the stuff you need to do your job. Again, stick with small and D-rated where you can live with it on the internals.
There is one thing I always except from the "smallest and D-rated" policy though, and that's the Fuel Scoop. There's two reasons for this:
I don't want to spend forever scooping fuel when I need it.
Fuel Scoops are massless anyway.
If you're gonna carry one, fit the biggest Fuel Scoop your ship can carry. Class doesn't affect scoop rate as critically as size does. For your Type-6, a 5E scoop will serve you just fine if that's all you can afford - and a max-sized, A-class scoop does indeed cost a great deal in comparison to the rest of the ship. Still, the higher in class you can go (while keeping the maximum size), the better! If you don't max out the Fuel Scoop's size though, you'll feel like you're trying to suck up stars through a coffee stirrer.
Last, make final adjustments to the Core Internals as needed to accommodate the power demands of the Optional Internals and Hardpoints that you've outfitted, as well as other performance requirements of your play style (like better Thrusters if you really need maneuverability in normal space).
Once you've done all that, take a look at your build and see if it still meets your desired per-jump and per-tank ranges. If not, you'll have to decide what options you want to sacrifice to achieve those goals. Or, do some Engineering. Or just upgrade to a new ship.
A Type-6 Build for You
Based on your original post, I'm guessing you want to do some long-distance passenger runs. Taking this into consideration, along with some other recommendations I'll cover below, here's a Type-6 build that should serve you well. Its maximum jump range is a little over 29 Ly (27.24 Ly on a full tank) - more than a 20% increase from your previous build.
Type-6 Unshielded Passenger Transport
With that build, your Core Internals are optimized for jump range and heat tolerance, and you're trimmed down to just the bare essentials that you'll need in the Optional Internals for passenger transport and exploration.
Note that I said and exploration. If you're going to be traveling far enough that jump range really matters to you that much, take along some scanning gear to earn extra credits along the way.
The Advanced Discovery Scanner will capture all celestial bodies in a given system, whereas the Basic Discovery Scanner has a very limited range - and each body you find with the scanner will grab about 500 CR from Universal Cartographics. It doesn't sound like much, but it really adds up over long hauls.
The Detailed Surface Scanner is for when you run into something interesting on the way. Check your System Map on every jump. Look for things like Earth-Like Worlds, Water Worlds, Neutron Stars, Black Holes, and White Dwarves - these are all very profitable in terms of value-per-scan, if you fly out to them and scan them with a Detailed Surface Scanner activated.
Exploration gets even more profitable if you happen to be the first person to return with detailed data for the bodies you scan. Google around, and you'll find plenty of information on how to make money with Exploration and it's something you can easily do at the same time you're ferrying people about.
With that build, you do still have to be a bit mindful of your power management. As long as you're not powering on more than one AFMU at a time, you should be okay. In any case, I've set the power priorities in there so that even if you do end up short, Life Support will always be up. And that's important since you've only got seven and a half minutes of reserve oxygen in that module.
Speaking of the AFMUs, do some Googling and read up on them if you don't know how they work. The short of it is, they're just there for when something goes wrong and you take some module damage. Generally, you hope to never need them. Also be aware that they can't be used to repair your hull.
One thing missing from that build, that you had in yours, is Shields. Flying with or without Shields is a risk/reward proposition that you'll have to decide for yourself. If you're transporting folks that other people want to kill, through densely-populated space, and spending a lot of time in-system between jumps, then you might want some Shields. If you must, I suggest going for 3D - just enough to keep you alive while you boost away and wait for your FSD to spool up and jump out. Do note that this will cost you about a quarter-Ly in jump range though.
