ReplicaR

So, this is the review of the actual catback. Back when I was doing research on which catback I want to get, I wanted to make sure that whatever I get will at the very least be a quality piece. Improvement in the sound was a requirement, and if I were to break 300 rwhp mark, that would be cool too. If you guys remember, the car made 284 rwhp in 4th, which would have been 296 rwhp in 5th (1:1 gear) if it hadn't been for the top speed limiter at 145 MPH).

From all options, Invidia seemed to make the most sense, and after reaching out to them directly, they were able to give a better price, so I decided to get Invidia.

The good: Invidia has a pretty quality built exhaust, and I was overall very satisfied with fit and finish, although there was a problem with the fitment of the tips. My guess is that at some point they changed the diameter of the piping, because the website mentioned 60mm pipe, but in reality it's 2.25 inch inside diameter, therefore tips were for bigger pipe, and required a trip to muffler shop to have them welded in. The rest of the piping is pretty good, nice smooth bends, clean welds, nothing to complain about. The exhaust is definitely on the quiet side. At idle it only registered 63 DBs (57 DBs stock) and at wide open the meter peaked at 89 DBs (87 DBs stock). During the daily drive, it's barely noticeable, which is actually great because I didn't want a loud exhaust or something that would annoy me daily.

The not so good: This exhaust is heavier than OEM catback. OEM complete system was around 61 lbs, while complete Invidia kit is around 73 lbs, so total gain of 12 lbs over stock. The power isn't terribly impressive either. While it is a substantial step up in pipe diameter, particularly in the rear section where it goes from 1.5 to 2.25 inch diameter, the chambered muffler slows down the flow of the exhaust, and therefore on the dyno it only picked up 4 rwhp at the peak. Most of the power difference was up on top, above 5500 rpm.

Test conditions: All the testing was done on the same day roughly 1 hour apart from each other. All pulls were done on DynoJet dynamometer, in 4th gear due to top speed limiter restriction. In 5th gear (a true 1:1 gear test) the car was making 5% more, so you do the math. Before people start chiming in how this requires a retune to fully optimize the catback, the tuning is not actually required. The Air to Fuel Ratio was the same between two runs, nothing else is changed. The tuning that you would do on a catback would affect stock setup in the same exact way.

Chambered vs Straight Through Mufflers: After seeing the results of the dyno, I got curious to see what would happen if I were to do a simple muffler swap. I went to the exhaust shop, and had them cut out the Invidia Muffler and replaced with Magnaflow Performance Muffler setup. While the sound at wide open throttle improved, the overall experience just turned into total misery. With my daily commute and the fact that the car is automatic, I was stuck almost exclusively in the drone range of the motor, which means that by the time I would get anywhere, I would have a splitting headache. I didn't even bother to find out if the straight through made any more power, because whatever the difference was going to be, I knew that I would not keep it like that, and would opt for quiet over 10 hp max.

Now, for a bit of show and tell.

Video of Dyno Pulls


Stock Exhaust.







Stock pipe diameter vs Invidia pipe diameter





Invidia Q300 Installed





Dyno Comparison

blnewt

iTrader: (13)

Wow! Now that's a DIY on how to do a proper review, excellent work there!

Dzionassi

What is your rpm drone rpm range with straight through muffler?
On my exhaust it is 1000rpms to 3000rpms....

ReplicaR

With Magnaflow I've experienced drone from 1500 to about 3000 rpm.

Dzionassi

Same thing happens to me when i change stock catback to tanabe catback( was thinking to add Helmholtz resonators...)

vq37_

What do you think about pairing it with invidia TP's? any gains/major sound difference?

ReplicaR

Per class rule which I am going to participate in next year, I'm not allowed to modify or remove catalytic converters, but I would imagine it would be a pretty significant difference by adding test pipes or even high flow cats for that matter. This is not my video, but here is one of before and after adding HFC to Invidia Q300 equipped G37 sedan.

vq37_

Sounds great even without the HFC, not too quiet and not too loud. I'm still waiting to pick up the q300, and test pipes sometime this week or next.

ReplicaR

A bit of an update. A heat shield needed to be either trimmed or removed all together around the X-pipe section, because the exhaust kept banging on the heat shield. I opted to remove the heat shield, as I don't think it's completely necessary there.

vq37_

Do you think that it would be able to fit a 2012 g37x sedan? The website I ordered it from says that it will fit all models of the G37.

ReplicaR

You can always reach out to Invidia directly and find out for yourself. I would not know if the catback fits on AWD model as well, since I don't know how different the underside is.

slartibartfast

iTrader: (7)

Awd exhausts are different than respective rwd model.

vq37_

So I was emailing the place where I ordered the Q300 from, and he got in contact with invidia with my part number and said that "it is a confirmed fit for the G37x, the previous versions of that part number did not fit the x but they redid it a little bit ago and it does fit."

slartibartfast

iTrader: (7)

That's good for all you awd guys.

MerakiAutoworks

iTrader: (1)

Very nice review!!


-Josh