Exhaust sound and Tuning?

[08DarkCandyGT]

Im hoping someone can help. I have stock exhaust with GTA axlebacks. I first got a no tune S&B intake. Car ran ok not to much different. Then i got an SCT X3 and used the 93 canned tune. Could not find my intake on the list and picked K&N since they were both no tune. Cars exhaust got much louder on throttle and it had good low end power. Then got a Brenspeed tune. 93 Perf. Car woke up with good throttle response but more power after 3K.
The thing is the exhaust note really mellowed out and the low end power seemed to be gone. What is the reasoning for the change in the exhaust sound and more power down low? Is the car running lean with the SCT tune and richer with the Brenspeed or is it the timing?

[Nino]

Could temperature be a factor? If you felt more power and louder sound in the cooler months compared to hotter summer days, that may make sense. Temperature may could be a factor in that case. Or it could be a combination of temp and tuning like you mentioned.

-Nino