I have an American Standard toilet that fills quite slowly. It's a 1.68 gallon flush and takes nearly 2 minutes to fill. By contrast my Drake 1.68 gallon fills in about 45 seconds. The current fill valve in the American Standard is a Fluidmaster 400. I took off the cap to clean the valve, but there was no sediment, and it did not change the fill time. As it turns out, I have an extra Toto TSU99A.X fill valve on hand. Is there any reason I shouldn't just pop that into the American Standard toilet? Although it says Toto on it, I believe it's the same as a Korky model that is marketed as a replacement for any brand of toilet in which it will fit.