I'm trying to build a domain grabbing application, which will be able to send handreds of request per second. I know eNom has limitation of one request per second, so I want to know which reg company don't have such a limitation?

Thank you!!!

None

It's not an Enom limit. It's a limit on the main database. Each account has a limit. To do more than that requires doing like Snapnames and others do, having multiple accounts.

Get an account at every registrar, then have a brother get one at every registrar also, then you can do frequent checking. You could probably do that for around $100,000 investment.