put the greddy sp2 on my z dynoed it today to find out I made 10 hp less than 4 months ago how is this possible?

 

That does suck, you should atleast see some small gain or at minimum stay the same, considering differences in atmospheric differences. Like if today was 90 degrees @ 90% humidity, and 4 months ago was 40 degrees @30% humidity, then today would yeild a lower dyno... However, with an upgraded muffler hopefully it would dyno higher no matter what, or atleast the same.

 

Maybe today you put out less power for some reasons mentioned. What you have to do is look at the SAE corrected numbers for your original dyno, and the SAE #'s for this one. I think you are looking at the actual numbers which is what your car did on that particular day.

 

too many variables to consider... for one, did you use the same dyno for your baseline vs your sp2 installed?

if not... that's your first and most obvious explanation

other reasons, as mentioned above, would be whether the runs were SAE corrected, other mods (if any), car condition (recent oil change?) etc......... again, too many variables

even if the sp2 really does put out lower numbers than the stock exhaust, you're still lightening the car by a dozen or more lbs.. that's worth mentioning as a performance increase as well

 

What about resetting the ECU? Think not doing this could have anything to do with it?

 

Same dyno same amount of time between oil changes the temp was around the same both times hmm what would comparing my non corrected # do?

 

SAE corrections (at this time of the year anyway in most of the country) are usually lower than non-corrected numbers.

And I wouldn't even attempt to compare dyno's done on different days with different mods.

 

i second that, i dont know if im just freakin out but when i bolted on my new system it felt sluggish, but i really dident care because it sounded so good. then i did technosquares reset process, and viola, it feels perfect now. i could just be losing it though... but i swear it helped.