Gordon's cup

I'm not a big drinker, and I mostly drink beer, but we recently acquired the start of a liquor collection, and I enjoy trying new things. Jon has made me a couple Gordon's cups, and I must say I like them quite well. We got the recipe from an issue of Bon Appetit. The first time, he went by the recipe. The second time, he increased the simple syrup just a little and added a splash of club soda. The first one was a lot stronger, both in alcohol and the herbal, almost peppery taste of gin. The second one was less intense, and I really liked the slight fizz. We will be making these again. Here is the recipe, with our changes in italics.

2 1/2" slices of cucumber, peeled
Juice of 1 lime (we decreased to 1/2 lime)
1/4 cup gin
1 1/2 tbsp simple syrup (we increased to 1 3/4 tbsp)
ice
splash of club soda

Muddle the cucumber with the lime juice in a cocktail shaker. Add gin, simple syrup, and ice. Shake, then strain into glass. Add club soda.