Hello & welcome to SPCR!
Thanks you, though I've already been lurking for quite a while.
I have tried a number of setups like this, with success. Try running fan#2 with a thermal controller. When you turn on fan#1 in the airflow path, fan #2 can actually slow down. This is caused by the positive pressure on fan#2, which allows it to blow enough cfm to keep the sensor/CPU at the same temp at a lower rpm. Hard to explain, I know
That's pretty much what I was thinking. The 2nd fan would kind of help exhaust the slowed down air coming from the heatsink and make it easier for the 1st one to blow, or something like that. I was just hoping that someone would know for sure if it helps at all, but looks like I need to experiment a bit or just go for one fan.
Cutting out the stamped metal grills probably helps more, both for lower noise and better air flow.
I know, but I'm still a bit afraid of cutting my newish p150. I currently have the Antec stock fan at the slowest position with Ninja, and Ninja's fan, slowed down to maybe ~6-8 volts with resistors, cooling my hard disk. I think I'm going to replace those with Nexus fans first and see how they do.