Here is my version of the cartridge straw mod for the 510. The stirring straws I have are access to are the single round straws. These straws are too large to use in their stock form. One solution to this problem is to flatten them with your thumb nail and fore finger. The first picture shows an unmodified straw along with a flattened straw piece cut to length.
You shouldn't flatten it too flat because you will want some tension later to hold the cut straw open. I will make that clear later on.
Here is more pictures showing the stock cart and filling.
Now trim off the edge of the filler to make room for the straw.
Now you will need to cut one edge off of the straw.
Here is what your straw should look like now.
The entire length of the straw is open to aid the wicking action by evacuating the air from the filler material. Even if the filler pushes on the straw and closes this gap it will still evacuate the air. It is simple to open it up manually at any time with a paper clip.
I usually cut a taper on the bottom of the straw even though it isn't required. Now you can put the filler back in leaving some sticking out so you can insert the straw.
The last pic shows the straw in place in the cart.
I have been using this version of the straw mod in all my carts for at least a month and I am amazed at how well it works. Without the straw I usually would have problems getting a good draw after just a few good hits. Using this method I can vape probably at least 8 to 10 drops of liquid before needing to top off.
As with any of the straw mod be careful to not over fill the cart. If you over fill there is a good chance you will get liquid past the atomizer right into your mouth. Nicotine is poison and you should avoid any unnecessary contact with your skin or your mouth. Also you can get liquid to leak between the atomizer and the battery. This is easier to do with the thinner liquids. Filled properly, this mod will really enhance the e-cig performance dramatically.
This modification is not a permanent change and can be reversed at any time.
I hope this helps someone.
Kevin

You shouldn't flatten it too flat because you will want some tension later to hold the cut straw open. I will make that clear later on.
Here is more pictures showing the stock cart and filling.

Now trim off the edge of the filler to make room for the straw.

Now you will need to cut one edge off of the straw.

Here is what your straw should look like now.

The entire length of the straw is open to aid the wicking action by evacuating the air from the filler material. Even if the filler pushes on the straw and closes this gap it will still evacuate the air. It is simple to open it up manually at any time with a paper clip.
I usually cut a taper on the bottom of the straw even though it isn't required. Now you can put the filler back in leaving some sticking out so you can insert the straw.

The last pic shows the straw in place in the cart.

I have been using this version of the straw mod in all my carts for at least a month and I am amazed at how well it works. Without the straw I usually would have problems getting a good draw after just a few good hits. Using this method I can vape probably at least 8 to 10 drops of liquid before needing to top off.
As with any of the straw mod be careful to not over fill the cart. If you over fill there is a good chance you will get liquid past the atomizer right into your mouth. Nicotine is poison and you should avoid any unnecessary contact with your skin or your mouth. Also you can get liquid to leak between the atomizer and the battery. This is easier to do with the thinner liquids. Filled properly, this mod will really enhance the e-cig performance dramatically.
This modification is not a permanent change and can be reversed at any time.
I hope this helps someone.
Kevin