Car = 07 G35s Sedan w/ Stillen Short tube intake

Option one: Axle back exhaust and ecu reflash

Option two: Axle back exhaust and HFC's

Option three: HFC's and ecu reflash

I've been leaning towards option one using the Tanabe Medalion Touring and upRev reflash. This way I get (IMO) a great sound from that exhaust and the little bit of a power bump, better throttle response and better A/F ratio. Correct me if I'm wrong on thinking that.

Inevitably I will do exhaust, HFC's and tune one day just can only afford two of the three to start with.

 

You won't gain much tuning a basically stock car because an axle back makes no difference other than sound. You might be lucky and gain 1-2hp from the Tanabe. Your AFR's will not change much if any so tuning wouldn't be necessary either.

If I was you, I'd get a full catback and forget about the reflash for now. You'll get a slight power bump which you might feel at high RPM as well as the sound.

Or if you want power go with HFC + Reflash.

 

On that note, will AFR be affected too much (i.e. dangerously) by going with a catback, but forgoing the tune at the moment?

 

No. catback alone will not alter the AFR much. My car was seeing around 13.1:1 ratio at WOT with catback only.
with intakes it went up to around 13.4:1.
After adding HFC's it was at 14.2:1.
After ECU tuning we added fuel and kept it at 13.2:1 while keeping the ignition timing around the same as stock. That's where it made the most power.

 

Cool. Thanks

Speaking of AFR's, mine with just an SRI is in the 11 range at WOT, any thoughts on that?
Here's a vid, notice the vertical graph on the screen, it hovers in the 14 range as we move up the gears, then goes to 11x at WOT.

 

Did you do any dyno runs in stock form?
Intakes can sometimes screw up MAF readings and cause the engine to go overly rich to compensate, although 11.X is pretty rich for N/A. ECU tuning can bump up the AFR and help you gain quite a bit of power.
It could also be the widebands not reading correctly. Most dynojet AFR sensors that are installed on the exhaust tips will read around ~1 point leaner than the actual AFR that the stock widebands read. I'm not sure about the ones used on mustangs though, could be a similar situation.

Do you have Uprev cipher?

 

Get a set of BERK'S HFC's here on our MARKETPLACE under vendor exhaust and don't consider a tune until you've installed a real cat back exhaust. OE cats is where the main restriction is, I'm surprised anything flows thru them. MotorDynes exhaust is the best bang for your $$ and best results....HP and sound!
Gary

 

Thanks for the opinions. I think I am just gonna start with exhaust work. Tuning and HFC's would be an option but I understand what ya mean about the OEM mufflers being very restrictive, also heard a sound clip of another g (same specs) with HFC's and OEM exhaust and I didn't care for the sound too much.

 

Random question: Does anyone know the diameter of the stock exhaust on 07 G35S Sedan?

 

2.25"

 

I think it's more of the y-pipe being restrictive than anything else.

Thanks for the input! I don't have a stock run. I thought 11's were okay, like you said it is about average for n/a. By the looks of it, i could probably gain something just tuning with the intake.

Then again, you also have a point about the wideband, i'm not sure where they put it, the area was blocked off and the closest i could get to was from where the video was shot. I still think the run was a fluke though, on both runs they stopped at 6.5k rpm for some reason. I don't have anything at the moment but looking into it.