Hey folks.
looking to add an exhaust and intake to get some extra hp. What is best recommendation for a 2010 G37X coupe.
what should I expect for hp gain? Ballpark.

 

Not too familiar with coupe exhaust options, but I'm sure the coupe exhaust thread will answer many questions: https://www.myg37.com/forums/g37-cou...st-thread.html

Intake depends on budget and expectations. If you're going all out for max gains, 3" admintuning intakes. It youre looking for most horsepower/$ spent, Z1 intakes are one of the better options. Z1 outperforms other 2.5" intakes by a tiny bit due to the velocity stack filters, but Takeda and Stillen are not too far behind, just cost a lot more for the same gain. Stay away from short ram intakes, and if you live in an area where it rains regularly, avoid Nismo style intakes (injen) as they often like to drink water.

Disclaimer: all numbers are based on my personal testing experience and research, and other people may have different results.
From just intake and exhaust with no tune, depending on what setup you go with, you may be running a bit too lean and can do bad things to your engine, so a tune is highly, highly recommended. That being said, the horsepower numbers won't be too impressive. The cats are a gigantic restriction and really are the gate to more power. With just exhaust and intake, taking into account torque converter and AWD power loss, around 285-295 wheel with fairly low torque of around 215-230 lb-ft. I'm just going off my dyno numbers for my sedan. Once you upgrade the cats to test pipes or HFC, you can expect to easily break that 300 threshold and get 305-310 wheel. Slightly conservative numbers, but don't underestimate how much power is being lost to the 7AT and AWD system.

 

Intakes... it matters between short-ram and long-tube.
Exhaust... it matters what you do or don't do with the cats.

So given the incredibly simplistic ask, the equally simple (un-tuned) answer is 5 to 15 hp.

Welcome to the forum.

 

3.5 intakes or nothing

 

What Hexotic said

"The cats are a gigantic restriction and really are the gate to more power."

THIS!!!!

I just ordered some FI test pipes - they might t be here by x-mas, they are a bit behind due to COVID.

money to HP, it seems the biggest gains are going to be getting rid of those pesky cats. Then finishing it off with a CBE that does good against the drone. and a tune.

 

Cold air intake, High flow cat, Catback Exhaust, get it tuned and call it a day