Low pressure blowback markers are a very popular thing in today's paintball world. There are many myths as well as facts about what LP is and what LP will do for you. I'd like to try to sort out the myth from the fact, as well as help anyone exploring LP see what they may need to convert their blowback to a LP marker.

LP will:
• Help reduce ball breaks caused by air pressure
• Reduce CO2 shoot down - You don't need as high a pressure to fire, so when CO2's output pressure drops it won't effect you
• Reduced noise - you'll have less gas to make noise with
• Consistency - Due to the regulator, your shots should be close in FPS, resulting in better accuracy (See my guide on accuracy)
• Give you field bragging rights - LP is cool
• You'll get a great knowledge of the inner workings of your marker - You learn how each part in the marker interacts with everything else.

LP may (these benefits are debatable) :
• Increased gas efficiency - LP markers replace pressure with volume. However, if you were using higher pressure and did not reduce the volume (Simply turning the regulator's pressure down without any other tweaking) and fire like that, you likely have gained some efficiency.
• General consistency(Accuracy) beyond that of just the reg - There is no evidence either way on this issue. This may simply be a result of having replaced several of your stock parts with different, usually higher quality parts.
• Reduce marker wear - Less pressure may put less strain on parts, but there is no evidence that pressure is a major cause of wear.
• Reduce marker kickback - Air pressure isn't what causes most of the kickback, but it may help slightly.

LP will not:
• Increase your range - You're still firing at the same FPS, so range will be the same. See my Range guide for more info.
• Make you a better player - You won't magically learn skills by going low pressure, just like you won't magically learn skills by buying a new marker.

The goal is to get your marker running below 400 PSI. Different markers will need different adjustments, but just about every issue here will need to be addressed.

Regulator - The most important part to get consistent operation, as well as pretty much the only way to actually lower the actual operating pressure. You need one that has a high flow rate and adjusts well at low pressure. A good reg to look at would be one that can switch from high to low pressure with a kit, or has a range of 200-800. Some Piranhas come with the PE reg, and that is acceptable, but not the best. Other blowbacks will need a new reg even if they come with one, as the are usually of a lower quality.

LP Chamber - A Low Pressure Chamber stores some extra volume to help with reduced pressure. Most LP chambers are created equal, so get one that looks nice on your marker. They often come with high flow vertical adapters, so that may effect your choice as well.

High Flow Vertical Adapter - Some vertical adapters on older Spyders and Piranhas aren't built for high flow. You can replace them (new LPC chambers often come with high flow versions), or simply drill them out a bit. I would recommend making a second hole in the ASA of the vertical adapter instead of widening the first hole. Make sure that the LPC connection has high enough airflow.

Turbo valve and high flow valve pin - Many aftermarket valves have a high flow pin already, so replacing the valve and pin is simple. Piranha G3s all have a turbo valve stock, as do some of the newer spiders, but need a better flowing pin to get better low pressure. You can simply shave it down yourself, or you can get a pre-done one for $10 or so (I'll have pics of a normal and high flow pin for a Piranha up soon). One of the better valves is the Madman Rocket valve, which is fully adjustable and has a self contained pin.

Bolt - A high flow bolt helps a lot. You can remove the Venturi from the bolt in most Spyders and Piranhas, or you can replace it with something like a Delrin bolt with a high flow pattern. The high end delrin bolts also help by lightening the load on the bold/striker assembly and reducing friction. Spyders have several bolt options, while Piranhas have to be a bit more creative.

Barrel - As long as you have a barrel that has at least 6" of unported length, though 8" is better. A good, well honed barrel, will help you increase your FPS to fire at acceptable speeds, allowing you to run at a lower pressure.

Polished Internals - On Spyders, polishing your bolt and striker where they wear on your marker will help reduce friction. On newer Piranhas, they have nickel and ceramic coated internals, so they don't need this, though using a polish on them without sanding them won't hurt. Dark Horizons has a Titanium striker that could also help, but I'm still researching that.

Spring kit - A spring kit that lets you replace your main spring and your valve spring is a good idea, as you will be doing a lot of tweeking. It never hurts to have choices, and most kits are relatively inexpensive.

Pressure gauge - You want one that lets you know what pressure your marker is running at. You can get them pre-installed on your Vertical Adapter, or you can get one installed there. Remember it needs to be on the side beyond the regulator in where t

Anti-siphon tube - A must for any drop forward CO2 using marker, under any circumstances.

Expansion Chamber - If your reg can take CO2, you won't need one. If your reg can't take CO2, then you probably shouldn't be using CO2. An X-chamber really doesn't help a marker much. Anti-siphon tube works much better anyway.

The idea is to get your marker to run around 280 FPS with the velocity adjuster at 1/2 - 2/3 of the way up. This will let you use the velocity adjuster to tweak the speed a bit, while using the regulator to make major velocity adjustments.

First, set the velocity adjuster to where you want it to be at when you're firing at 280. Then adjust your regulator till you're able to dry fire rapidly with your marker recocking. After that, chronograph your marker, adjusting the regulator till you're firing at about 280 consistency. Note your pressure you're running at with that spring combination, and then repeat the procedure, adjusting the main spring and/or valve spring. Remember, it may not always be the lightest valve spring and heaviest main spring that results in the lowest pressure.

The end result of all this will be a blowback marker that will be able to fire at 280 FPS running at 350 PSI or less. The results may vary depending on your marker and the parts used, but the goal of getting the marker to fire under 400 PSI can be accomplished.

Is it worth all the money and time to get your marker to fire like this? That's a personal question. I think that the fun of tweeking your marker is well worth the time and money, and many of the parts can be modified by hand, making the cost cheaper anyway.

Have fun and good luck.