I bet the stock heads flow real well if it's making power up to 7000, plus the oversquare bore/stroke and 2 throttle bodies are great for High rpms. A narrow exhaust and restrictive factory cats choke up a good breathing motor, an engine to me should be as power efficient as it can with external parts.

 

With the car being tuned for them of course, I thought this was common knowledge by now?

 

Test pipes alone? Stock intake and exhaust pipes and mufflers?

 

Yep. One guy on MY370Z got 24whp/20tq from test pipes and K&N drop ins, nothing else. His name is Sysopz I think.

 

What were his baseline numbers? A dyno is not a dyno is not a dyno.

 

New dyno after test pipes and retune - Nissan 370Z Forum


No idea, just says before and after the test pipes w/ tune. The 24whp claim is from a guy further down that post. Either way, the PO's main question is which is better and I was asking how that other guy couldn't feel ANY difference after the upgrade..


The real answer is they are marginally better than high flow cats but they ARE better, cheaper too. For me, I'd gladly lose 1-2hp and ONLY run HFC to avoid the smell and CEL but that's just me..

 

I applaud your decision. Smog and unburned HCs are no good.