The Patented Torque-Line Head will add power with stock jetting or fuel mapping.. The added cooling alone will add some power.. But, with stock jetting/mapping I think the power gains will be noticeable but not "blown away" power (except in the cases of some CAT head designs.)
There are also some mis-conceptions as to what is "LEAN" Jetting and as to what is "PROPER" Jetting... The RK Tek head is the only head that will allow you to SAFELY jet down..
If an aftermarket head is not allowing for leaner jetting.. then it is NOT adding efficiency.. Now, you can add power without adding efficiency.. but adding power AND adding efficiency at the same time is the better option.. for sure!
OK, back to the topic at hand....Jetting???
Ok, so we have determined that the RK Tek head will add efficiency.. and increased efficiency requires LESS jetting.. NOT to be confused with LEANER jetting.. After-all.. we are dealing with Fuel/Air ratio.. So, let's say the the PROPER F/A ratio for a stock headed engine is 1:12.. If you jet it down you ratio gets LEANER.. say 1:14 or even 1:15... OK.. THIS IS LEAN JETTING!! PROPER is 1:12..
OK, now you add the RK Tek Head... Now with stock jetting your 1:12 F/A suddenly becomes too rich . OK... THIS IS RICH JETTING!!.. Why?? Because the head combusts a higher percentage and therefore; requires less fuel to keep the chamber cool and safe from detonation. So, you have changed the head ONLY and now your F/A ratio is RICH with respect to what your engine NOW requires! You are not at the PROPER ratio anymore.. So, what needs to happen?? Well...you need to get back to PROPER F/A ratio FOR YOUR ENGINE!... So, you need to jet down to get BACK TO to proper F/A ratio which now may be closer to 1:12.5 or even 1:13..
So, are you going lean on the jetting?? NOPE!! You are putting it back to PROPER ratio... So, this is NOT leaner/on the edge jetting.. It is SIMPLY putting everything back to NORMAL ... Now, of course, if you were to jet down with the stock head or some other aftermarket head that did not add efficiency (all of them).. THEN this would be LEAN/ON THE EDGE jetting.. BUT.. you added efficiency with the head.. so you are not going leaner at all... MAKE SENSE!!
So, this idea of the RK Tek Torque-Line Head requiring LEAN jetting to function is a huge mis-conception.. It requires a different F/A ratio BUT to achieve this new ratio.. a lesser main jet is required... YOU ARE NOT AT LEANER JETTING.. YOU ARE AT PROPER JETTING AND THE SAME F/A RATIO (as far as your engine knows) as STOCK!!
OK.. After reading all that, hopefully you understand what COULD be happening inside your engine.. The reality is... the F/A is not really changing..BUT.. the engine is reacting like it has changed... The bottom line is: The Torque-Line Head's patented design is new technology and allows for a leaner F/A ratio and no reliability issues!! This head is that advanced!!
This idea that the larger and more powerful the engine the more fuel it needs is not always correct when you consider the other players at work like efficiency and internal flow characteristics (pipe effects and porting arrangement). I can tell you that the more powerful the engine is.. the less restrictive the exhaust outlet needs to be will always be true...