BitGo supports Dash InstantSend. Note, at present, there are not many Dash masternodes utilizing this feature, so BitGo cannot promise that the recipient will receive their funds instantly. When sending Dash InstantSend payments using the BitGo UI, you simply need to select the checkbox for sending via Dash InstantSend. When using the BitGo API, you will want to send the transaction including the parameter "instant=true". We cannot provide a list of wallet providers that can receive InstantSends at this point, but expect to see more network adoption of this feature in the near future.
Alternatively, you can set the priority of a Dash transaction by sending Dash payments using the API using the numBlocks parameter like you can with Bitcoin and other UTXO-based coins. Dash’s smallest denomination format is called the Duff, which is equivalent to .00000001 DASH.
Fees on the Dash network are calculated as follows:
Standard Dash transaction: .00001 DASH per kB of transaction data
Dash InstantSend transaction: .0001 DASH per transaction input