It is tuned crank minus the silicone. I talked with the factory and they believe the silicone doesn't add anymore power or performance but from my own research, I have found the filled crank will assist with crank velocity and flow which assists the engine in low end response and in theory should help with fuel mileage as well. The sleeve closely resembles both the sport and tuned version. Both engines in the day had the same timing specs, size, shape, port count etc. The only main difference is the sleeve on the TQ doesn't have the tear drop cut on the bottom of the transfer which would put it closer to design of the old sport engine. I have switched the two sleeves between the same engine before and it was very difficult to tell the difference. The tear drop cut can make a difference but it needs to have the right entrance angle, size, shape and length to make it work properly. I do what is called backporting the window and what that does is changes not only the angle of entry but also the velocity of the charge to act as an invisable barrier to keep the incoming charge from short circuiting with the outgoing charge. It basically changes the loop scavaging effect by pushing the loop rearward in the cylinder.