I have not yet been to the dyno to check the benefits and horsepower increase of the exhaust manifold, because it is summer and the weather is very worm in Greece. Also I will fit more upgrade parts on the car in September. I can only tell you my impressions when driving the car. These are positive since I can feel the acceleration and power when I press the throttle (i can feel the acceleration after 3000rpm). I am not sure what is the difference with the OEM manifold since i fitted the DKNE manifold together with the compressor. From what i know the DKNE manifold is equal length, it is made of steel (not stainless steel) so it is light. Furthermore it is much cheaper (including the shipping charges) than the European exhaust manifolds and i was lucky since i did not pay any custom fees. Also DKNE shipped the manifold the next day i paid them (via paypal), and i received the item in Greece after one week. Lastly DKNE states that there is an increase in horsepower in standard IS200's (without sc) and actually they are waiting to send them the dyno charts of my car. I would definetely recommend the exhaust to Lexus owners. The noise is from the exhaust manifold is more droughty but not annoying, which i love it.