Most of this was quoted from OtterSC
Some upgrades work and some do not for the JT Excellerator line of paintball guns, for example there arenít any aftermarket grips that will on the JT Excellerator trigger frames. Here is a list of upgrades you can buy for your JT:
1. New Barrel - This should be the first thing to get before anything else. Any spyder barrels will fit the JT line of guns. The stock JT barrel is one of the best stock barrels ever for close range accuracy, but if you want long-rage accuracy or a barrel for LP then youíre going to have to buy an aftermarket one. There is no ONE barrel that is more accurate than another. I cringe when I see that statement that "XYZ" barrel is the very best. That is false! The best way to have accuracy is to make sure you match the paint you use often with a barrel of matching bore size. A good paint to barrel match will help give you accuracy and cuts down on wasting air. A new barrel will be quieter than the stock in most cases. A new barrel will also sometimes help in ball breaks. Get a barrel between 8-14". Actual studies on paintball have shown that it takes a minimum 8" for a paintball to get up to speed. Another 2-4" is a guide for the paintball. The remaining barrel is just friction on the ball, causing you to use more gas. Good companies to look at are CP, Dye, J&J, Lapco, and Smart Parts. You can get quality barrels for under $60.
2. Agitating Ball Hopper - Breaking paintballs? It may not be the bolt, as many manufacturers will claim. It very well can be the speed of the balls feeding into you marker. In a non-agitating hopper, the balls tend to get stuck before entering the hopper neck. When they do find there way down the neck, it could be the same time that the bolt is traveling forward. You have the BE eVolution, and the 9v and 12v Revi's to choose from. There are other hoppers that you can consider. But the above mentioned have been proven. These special hoppers will increase the feed by agitating the paintballs in the hopper with rotating paddles. Keeping the balls moving will help prevent the bottleneck that happens with non-agitating hoppers. There is also the AGD Warp Feed. This requires a Revi along with the Warp Feed. So, why get the Warp Feed when I also need a Revi for it. A good reason is that the hopper is moved from the top of your marker to the side. This is a much lower profile, enables you to shoot your marker sideways, and increases the feed into your marker. The only draw back is the feed is dictated by how the Revi feeds it. Sideways shooting, youíre probably good for 15 to 20 shots. Then you need to right side it up to refill the Warp.
3. Regulator - A good addition. It will make your marker more consistent which will give your marker potentially better accuracy. Be sure to get the right regulator for the gas youíre using. For CO2 - Palmers Stabilizer and Bob Long Torpedo is a great choice. Also, the WGP regulator for the Autococker and the PMI are not bad with CO2 and can screw into the JT 5.0/6.0. For Nitro/HPA - Vigilante are good or any of the CO2 regulators mentioned above. And if you do get a regulator while using CO2 and switch to Nitro, no problem using the same regulator. To add a regulator to the JT 3.0\4.0 you will need to do some modifications and itís not for everyone. For the 5.0/6.0 any regulator should fit into the vertical adapter. You may need to invest in a new ASA (that thingy that you screw the tank to), elbows, and braided hose or macro-line. It is possible to use the existing air lines with the use of a Metric to US thread adapter. Adding an anti-siphon tube to the CO2 tank will help keep liquid CO2 out of the marker.
Don't bother with an expansion chamber or even a gas thru grip. Expansion chambers will give the CO2 time to expand. But it will still give you velocity spikes that can add 20, even 30 fps. See not so great upgrades below for a better explanation as well as setup suggestions.
4. Spring Kit - An excellent way to fine tuning the velocity. Especially in really cold or hot weather when the velocity cannot adjust to where you need it. 32 Degrees and Maddman kits are popular. Also, while getting the springs, stock up on o-rings and get a Lapco cup seal. O-rings tend to break often. Especially when using CO2. The Lapco cup seal is made of softer material and doesn't scratch easily. This gives you a better seal than the stock one. Another small price item is a thread protector. This is a cap that screws onto the air bottles threads and proctects them from getting banged up. For you nitro tank users, I also suggest a fill nipple cap to keep dirt out.
5. Nitro/HPA Tank - This will level out any severe spikes that you often get with CO2. Even with a regulator. Your shots will be very consistent because it is simply air that we breathe that is used. Much more stable than CO2.
6. Trigger Job or Electronic Trigger Frame - There are many home modification instructions available online to reduce trigger pull on several sites. www.Spyder-Club.org
has articles as well. If you're not too sure of yourself about doing your own modification, go to Polecat Paintball and for $20 (at the time of this writing), you get a pretty nice one. Getting a new trigger frame may be an option. There are many to choose from. Some you may need to transfer your existing trigger internals to the new frame. If you do that, might as well do a trigger mod. Dye, Bob Long, 32 Degrees are good trigger frames. The e-frames are nice. Also, depending on the trigger frame, the holes that you have for the bottom line may change. JT stock frames have off-center holes. Some aftermarket frames have in-line holes and if this is the case, a bottom line adaptor is needed or get a new bottom line accordingly.
7. Drop Forward or Bottomline - While youíre getting a regulator, look into getting a drop forward or a bottomline. Stock, the JTs will use metric threads, including the hoses. Adding US threaded pieces will make adding aftermarket items easier. Drop forwards come in all shapes and sizes. Get one you like. Drop forwards with an on/off feature on the ASA are nice. No more gas escaping from your tank while you unscrew the tank. Just turn off the air, shoot the maker (without paint) until it no longer re-cocks. Also, look under your grip. Are the holes staggered? More than likely they are. You need to purchase an adapter that switches your staggered, off-center holes on the bottom of the grip to in-line holes. These can be found at G3 Paintball and Polecat Paintball. Expect to pay around $10 to $15. And don't forget about new fittings and air lines. For air lines, I suggest either SS braid or Macroline. Microline are too restrictive. Braided hose lasts longer, but comes in certain sizes. Macroline can be cut to fit and easy to replace, but tends to crack and leak easily. You can use the stock air lines. However, a Metric to US thread adaptor is needed. If you do get new air fittings, get ones that are inexpensive.
8. Polish Internals - Polishing your internals will ease the friction of your parts in the marker. This is not really a purchase item like the list above, but certainly a performance enhancing upgrade. Use 800-1,000 grit paper and use circular motions. Never use coarse sandpaper and do not create any flat spots. Clean off the dust and use a nice metal wax, like Mothers Mag. You need to polish the bolt, sear, valve pin, and the inside of the body where the bolt assembly moves. But do not sand the internal tubes. Just polish them.
* The following items are not really needed for a great shooting marker. If you have done all of the above, you have invested a lot of time and money into your marker. The next step into transforming your JT into a slick marker is to make it LP (or Low Pressure). You're more than halfway there if you have done all of the above upgrades. The next few steps are either purchased products and/or home modifications that you can do.
1. Bolt Ė The stock JT bolt is almost perfect for LP use, but if you want to squeeze every last ounce of performance from your gun you can buy an aftermarket one. Stay away from venturi tho. There is a dedicated LP bolt made by AKA called Lightening Bolt. This is a bolt that is manufactured in such a way to direct the flow of air to the ball. It also has no venturi. You can also get delrin bolts which are made from plastic and wonít cause so much wear inside of your gun. Good delrin bolts are White Wolf, Tarantula, or a nylon Swan Creek, but almost any spyder bolts will fit in the JT.
2. Valve - The stock valve is all right for normal use, but there is a better valve available for LP. It is from AKA called the Tornado valve. Diamond Labs made one before their demise that worked great. But the DL valves are extremely hard to find. You could use any of the turbo valves such as the Venom, 32degrees MagnaPort, or the one from Taso with close to equal results. The AKA is well worth the money. If not, then get a turbo valve.
3. Miscellaneous Modifications - There are other things to do for an LP setup. Try different spring combinations for the main and valve. You may find that a strong valve and a weak main will give you the lowest psi at the desired velocity. Adding a gauge is also nice. They are not accurate and they may be off by 25psi, but it will give you a rough estimate on what pressure you are at. Some regulators do not allow you to mount gauges on them, so you need to mount them on the ASA or the gunís body itself if it is important to you to have a gauge.