Peppers make sausage hot.
If you are talking about Hot Italian, the key flavor is Fennel.
NOT that it should be over powering,
like folks do in pumpkin or apple pie.
It's just the note that makes you think "Italian Sausage".
We don't love the anise flavor, especially the BANG you get when you bite
a seed. So after measuring it out, I toss it in a spice grinder and powder it.
Still get the flavor, just avoiding that huge shot.
Cayenne is what we use to put bite in our Italian sausage.
I like to work up our recipes. Buying mixes is like buying a casserole
and heating it up. We enjoy actually making our own stuff.
This site will keep you busy.
https://www.meatsandsausages.com/sausage-recipesDon't know where you are, or what's around, or if you get over this way (Bedford)
we have some Amish stores that sell spices in bulk. For about less than a bottle of
McCormick spice, you can get a good sized tub. They sell enough that it's not old.
The cost of a one batch mix will buy more than you would use in a year.
And you an tweak each batch until it's perfect to you.
Hint, a digital scale is indispensable.
I weigh the meat in pounds, the spices in grams.
That makes conversion easy. (Kilograms would be easier but...'murica!)
Work up the recipes in 10 pound batches.
Then if you have a batch that ends up at 12 pounds, multiply your spices by 1.2.
8 lbs x .8.....
Makes things much easier than needing .8 of 1 1/2 teaspoons, or
1.2 of 1/3 cup.