is there much to be gained going up from 181 delivery valves to 191's and above?

 

yes, they allow a lot more fuel to the injectors.

 

thanks for the reply, but i was hoping for a more detailed cost to benefit ratio. i currently have 181's in a 180 pump but i have a 915 pump i'm thinking of setting up, [maybe with 191's] but i don't want to do it if it's going to destroy my mileage. [ around 21mpg]