Hi from Norcal!

I have a 2005 G35 AT with the following mods:

5/16" Plenum Spacer with Iso-thermal Gasket & TB Coolant Bypass
Z Tube
HKS Catback

I want to get the most HP from the mods I have installed and was thinking of purchasing an Osiris Tuner or having it done professionally at the Z Garage...

My Questions...

Before I sink anymore $ into a 10 year old car what kind of gains would I see with those mods properly tuned?

How reliable and how well do the guesstimated email tunes perform that you get when purchasing the Osiris tuner?

Would it be more advisable to have the car tuned professionally?

Should I just go find a low mileage G37 MT and mod it?

I have also been looking at the M45s, does anyone have any opinions or suggestions about the M45?

Thank you in advance!

 

An Uprev tune will wake it up nicely. Hp gains we're talking about 10-15 at the wheels, but a lot more responsive with firmer shifts.

Its a much better value to purchase the tuner kit vs getting it done on the dyno, you'll pay about the same but with the dyno tune you only get the license flashed onto your ECU.. no reflash cable so you can't reflash back to stock and sell it used, perform OBD2 diagnostics, or reflash updates on your own.

As long as the person doing the Etuning knows what they're doing the tune can be just as good as a dyno tune, just no instant gratification of watching it on the dyno or seeing the dyno graph.

I personally upgraded from a 2006 G35 coupe to a 2006 M45s, absolutely love it. Only downside is the aftermarket support is very limited. (but that V8!!!)

 

Thanks for the advice... If I do decide to purchase Osiris I will definitely go for the Tuner version.

"Wake it up nicely" is exactly what I am looking for; not looking to do much more as far as engine mods, maybe a 75mm TB but still researching that.

I want to play with a new toy and that M45 has me sold on the interior, looks like a cockpit and the car itself still keeps that Infinti curve and prowess. Very hard to find a low mileage late model, I am assuming because people don't want to give up their M45.

The G isn't going anywhere though, she will stay in my garage along with the M45

 

I would stay away from the larger throttlebodys. Proven gains just aren't there.

M45 is hands down an awesome car. If possible get one with the factory aero package (pretty rare) it comes with a front lip and rear truck spoiler

 

Well, be it my opinion, but you might be happier in a 2007/2008 G versus modding the one you have. It (07/08) comes out of the box with more power than basic mods will get you on a second gen vq35, and you can then apply some of the same mods to the updated 07/08 VQ that you'd apply to the older G and take it even further.

As for the m45 it is nice car, but heavier than the g's to it becomes a wash versus a lightly modded 07/08 in terms of speed.

*comfort wise* i'd take the m45 despite the terrible gas mileage as the g35's are not the most comfortable 6+ hour road trip cars.

but ... my 2c

 

My M45 gets 19 mpg combined and 22ish on the freeway, very similar to a G35. Even though its heavier it is faster than a bolted G35, and feels very solid when driving aggressively

 

My 06-5AT sedan nets atm 28mpg (65) and 30mpg off the winter blend. But that just seems to be me and like two others on the forums after a really good tune with cam phasing and what not.

But it is my personal opinion that 22mpg is low.. but that's me so grain of salt and all that

 

30 mpg is extremely good gas mileage... I haven't seen any G35's consistently get that, usually guys are complaining about mid teens. When I had the 06 coupe I was getting low 20's, highest I ever got was 26 mpg on the freeway. With a tune as well.

 

I was fully prepared for 24-25mpg when I bought it. I considered it a 'fun tax' for getting to romp around in something with some level of Z heritage.

After the tune to 'up the torque' and 're-phase the cams' and re-time it to fight off the ping-monster I was seeing 375-400 miles on 13.x gallons on road trips before the 3.5-4 gallon shame light would come on.

I have yet to actually run a full tank on the road, I need to find a excuse to do so because i'd seriously like to know what 65-70mph over a full 16.x gallons would do.

 

that reminds me ...

OP, the shame you gas light comes on with 3.5+ gallons in the tank still. if you are dividing out by 20 your maths will be a smidge off.

 

Also note, as I just found out by experience... running 2.5.x ish quarts of 5/20 seems to really affect mpg. to the tune of 3-mpg for me which STILL baffles me unless I got a really awful tank full of winter blend.

Normally I have been running 2-2.5 quarts of the good synthetic stuff 5\20 for the extra detergent stuff. but the dealership dumped in all straight 30w oil and $%&* me the milage dropped out its *** on a Washington trip up I5.. oh yeah. I drive I5 and its super flat most of the time.

So my mileage again.. grain of salt.

 

You mix oil types and viscosities? Why?

 

Plus it's freakin' VIP!

 

Because he wants to replace his engine internals early some day!

 

Seymore, I messaged you about a tune, babe. Let's do this!