[SIMN]

Originally Posted by pokeybritches

5 horsepower from a real tuner is about the max you can expect, unless you've deviated significantly from stock hardware. I wouldn't trust anyone that told me they could gain 20 horsepower on an otherwise stock car. Additionally, power achieved on a dyno can vary by 10 horsepower between runs. So, I could easily show my worst and best runs of the day, and without changing anything, show a 10 horsepower gain from doing "mod x".

Catless headers with relocated O2 sensors and secondary race cats (like HJS) will provide the most power gain without going forced induction.

Originally Posted by SDCoupe

Seems like a 5% gain is not unreasonable. Manufacturers always set their timing low so that it won't knock on the worst gas it can expect to see in a particular country. I think this is why the 3.0si is rated at 265hp in Europe (instead of 255hp in U.S.), the octane is higher there. The tuners advance the timing so you essentially have to always use 91 otherwise knock could occur. 5% increase on 3.0si is about 14hp. Not huge but it's nice to say you are running 270hp.

You two say different?