I run an tuned IDM .12 nova based engine as my racing engine. It is jumpy and really sensitive. Lots of power but there are few days when I run straight through with a smile. A p/s/r set for idm costs more than a new sts d5r and pipe set! Not to mention the microcast pistons have a short life. The sts will replace it no problems. It is in my rrr right now and I have no intention of changing back to the idm. The sts idles smooth and is just as fast, in fact, fast enough on breakin that all the other drivers at the track running novas were asking about it. I cant comment on how it is race tuned yet because it is still rich! Even rich it is there with the novas once it clears out.