I have the 98' 2.5 and install the topspeed just now.
Similar to most of members, I have the drone starting from 2k RPM to 3k RPM.
I have read some other posts, and it seems that owner in 3.2 can replace the catless pipe from topspeed to reduce the drone with better air flowing.
However, with the 2 catalytic design in 2.5, there would be no catalytic at all after replacing the stock cat with the catless pipe.
Thus, I would like to see any 2.5 owners had solved the drone before?