Many things will cause a feeling of lost power due to added flow. When I added headers with only a pulley and pcm, it felt as though some of the low end torque had disappeared. Yet when the rpm'* increased faster than before and flowed better to allow for more top end power it was clear that the power didn't disappear, it shifted.
3" exhaust is a bit much and I'll even go out on the limb and to mention it is too much. My setup has been a test of exhaust etc. Only recently did I find that I am outflowing the 2.5" exhaust that makes up my system from the cat back.
N* throttle body
Mezeire water pump
8 rib belt
Gen V supercharger
All these mods above and I didn't appear to be outflowing 2.5".
Stage 3 heads
And I began noticing an issue with exhaust.
All these mods added up create a lot of flow. The 2.5" was good until the last two mods. Then the total of all the mods hit a level of outflowing.
00 Regal GS: All kinds of cool stuff.