Baratza Virtuoso/Wave Recipe Questions...

Hey guys!

I'm new to r/coffee and also relatively new to the coffee world! I have done a ton of research, spoken to baristas' and my roaster, and just can't figure something out.

So I'm here! My question is concerning my recipe. Here are the details!

I have a Virtuoso grinder, Wave 185 Brewer, bonavita gooseneck kettle, I use a scale and brew into a carafe. My recipe comes straight from the roaster that I use (I'm subscribed to Driftaway and got some help from Suyog from the site.) and is as follows:

30g coffee 500g water 200 degree temperature

Pour a 30 second bloom, then to 250g under a minute. Then pour 25-50g every 20 seconds until roughly 2:40 with brew time finishing around 3:35 total.

They recommend starting on grind setting 20 and working my way down to finding the size that gives me the best taste.

I tend to follow the recipe really well and don't have problems with my timing.

But I struggle with under extraction. I have so much trouble tasting the coffee and finding a difference in "notes" between say 20 and 18 grind setting. But i do get some sourness as i continue move the grind. It's more prevalent with the coarser setting, but I brewed a cup in grind 16 today and still get some sourness in my coffee. It's just under extracted.

All of my reading has showed me that the kalita should use a medium coarse grind that is similar to a Chemex. I'm way off that mark right now.

I'm trying to find the perfect balance here because it's frustrating always having to go finer. Any and all help is appreciated

TL;DR 30/500 ratio. 200 temp. Virutoso/wave. 3:30 brew time. Under extracted. Grind 16-20 settings.