Difference in 5 Gal vs. 6 Gal Help

Im gonna use up my last 2 cans of Ironman Porter Extract They are the 3lb ones which lets you make 6 gallons instead of 5 gallons like I am used to.
Anything I need to know before I use these up. Im just gonna use the beginning method with the dry yeast just to get it done before I move on to partial boil. I tried to make a yeast starter out of the 2 packages I had of yeast but they were to old and I got nothing from them.

First, you could just add less water and make it 5g. The biggest issue with 6g batches is you might not have as much space in the fermenter, and may need to use a blowoff.

it will be stronger if you leave head space. 5.5g and a blowoff tube. (depends on fermenter size)

If you make a 5 gallon batch as opposed to a 6 gallon, the gravity will be higher and you'll end up with a stronger beer.