If you put a better engine in the RS4 to replace the 15fe, you will blow the doors off any 4-tec. That is the 4-tecs only advantage over the RS4 3. 2-3 years ago, yeah, they were the car to get but why do you think they've pretty much disappeared from the race scene? People who do have them, just bash them. Just my opinion but you'll find others that will agree with me. Now with the stock engine, you might have to baby it up. Even with a 2-speed, racing pipe, and proper gearing might not be enough. To hold ground with the 4-tec , you should drop a O.S. or a Fantom engine ( cheap but have unbelievable power), you will beat them easily.
But correct me if I'm wrong.