so i got the hahn 3" exhaust. but since my car is lowered its hitting so i took off the muffler and the piece that bends over the rear axle. and left the rest of the exhaust on. (sounds killer by the way). my question is. i am now currently boosting 17 psi. i know our cars have the learn down feature, but i dont understand why my car lost HP. from my understanding turbo'd cars dont need back pressure so why am i losing HP?

 

How do you know you lost HP? Did you do a before and after dyno? Butt dynos don't count.

 

I think he is trying to say that he lost boost.

I would assume a turbo car would lose boost pressure if you go to a larger diameter exhaust system....

It is called efficiency, you are making the same horsepower with less boost.

 

Nah, what hes saying is, his boost went up! to make up for missing horsepower. Thats what hes thinking. When its colder out the boost goes low, when its hot out the boost goes up. Whats the temp outside?

 

how come my boost doesnt change hot or cold. didnt change with new intake either. always boosting at 16 psi

 

since our cars have this learn down feature, its kinda a double edged sword actually... You can also think of it as a learn up feature lol. when its hot out and the air running through the IC isnt cooling as well as it would when its cold out keeps the air somewhat more expanded, the ECM senses this and makes a boost adjustment to keep power levels from dropping.

Too answer your question in your first post, putting an exhaust shouldnt lower your Horsepower no matter what if your tuned or not. The car will make the 262hp at the crank. go get the car dynoed, you need proof before you make a claim like that. as for the boost staying at 16psi, thats normal. even after adding an intake and anthing else, the boost will only fluctuate with the temp of the air running through the IC fluctuating.

 

the temp is like 80 now. it was 90 and before i had the new exhaust and i was still only boosting 15 psi. i dont have the spare change to go and get the car dyno'd. it was just a question and i wanted to hear thoughts