Yeah, unless you want to keep your car 100% stock and pay dearly, there is none.
Chuck (RX-7 nut) built me a N/A ->turbo 6 port bridge motor... its still going strong after minor abuse.
He's also done a few other N/A -> JDM TII swaps that I know around here.
Its worth the drive down there, you will save the money you spend in gas on steep shop fees.

this thread has come a long way.