James ,You are misinterpreting what the RPM Act is.
First , the bill HR 3281 has not been passed yet , AND its purpose it to help protect motorsports from actions by the EPA regarding race only vehicles. .......It was written with much input by SEMA .
It will not however protect modifications on street driven cars that are subject to EPA rules.
Fire up that keyboard and contact your congressional representative and insist they back the bill.
We may not have much of a chance of it even going up for a vote in this congress , but it never hurts to make your representative know you're informed about it ,and let them know your vote will go to someone who will support it .
Here's a link to the SEMA site to contact your representative.
https://www.votervoice.net/SEMA/campaigns/45394/respond