Cool, I am excited to see the results. I plan on running the Greddy axle back and the Apexi mid pipe.

Steve

 

pretty certain just a 4-5" extension just behind the middle of the mid pipe .

 

I just got back from having the car dyno’d again. The new exhaust is on the car and it definitely feels quicker around town and when going WOT. So I expected a noticeable difference in graphs over my baseline.

The exhaust is an Invidia Q300 for a RCF, that was modified to fit the GSF. Today was warmer than the first day It was dyno’d. May 14th it was 77° when I got to the shop to dyno. Today it was 85° by the time I got there and the appointment was at 10am just like last time. After the hour plus drive we put the car on the dyno and it made 393whp and 354wtq. I was impressed because on the hot pull last time it made 383whp and we didn’t get a wtq output for that one because we had to change where the tach signal was coming from to get a good reading.

After letting the car cool down for 20 minutes with a fan on the engine and a larger fan blowing into the radiators. We took the fan off the engine and made another pull. She put down 403whp and 361wtq.

A gain of 11whp and 14wtq from the Invidia catback. I’ve looked all over and I don’t see anywhere where Invidia lists the power gains from the exhaust. So I guess that’s about the gain I should be expecting.

Either way it makes power all over the graph compared to stock. And definitely feels different when I lay into it. As well as just more responsive around town.

Here’s the overlay of the best two runs. The best from the baseline pulls, and the best from today.

 

Does the Invidia have high flow cats? Honestly, I was expecting it to pick up more considering how restrictive the stock mid-pipe and exhaust are.

Steve

 

I haven’t found specifics on if it does or not, but I don’t think it does based on the picture. I’ll message them
and see if they will tell me.

 

That’s good to know, atleast you confirmed there’s some hp gain with a catback exhaust.

 

Somebody responded to my email to Invidia that no the exhaust does not have high flow cats because it’s a “CATBACK” exhaust.

I thought we had secondary cats. But now they’re saying those are resonators.

 

Here’s the video of the pull with the exhaust:

 

Just put in an order for some PPE Un-Equal Length headers from RR Racing. At this time I declined to purchase the tune because I want to see what the headers will do before adding the tuning solution. I’m hoping to crack 430whp when the car gets dyno’d again with the headers. And then hopefully from there when I get the tune and overlay it against the full bolt on graph before tuned. I can see a noticeable difference in power delivery.

It does suck that it’s such a long wait for headers to be built. But hopefully it’s worth it and wakes the car up a good bit.

 

Very nice and I really like the look of your GSF.

I ordered a Q300 from Josh so it should be here late January, I can't imagine how loud your car will be with UEL headers and no cats.

 

It’s pretty tame when not on the throttle now. Inside the car still sounds stock unless you’re accelerating. Cruising literally sounds like stock. When you crack it open it’s still pretty tame compared to some catbacks so I think the Q300 gives a good mix of elegance and sound. The headers should make it sound pretty gnarly and I can’t wait to hear it.

You’re going to love it, did you get the titanium tips?

 

Thank you for doing this in stages so we can see the incremental increases with each mod!

 

No problem, I wanna see if the RR claims of 25-35whp from just headers or 35-45whp with headers and the tune or true or just claims that only show up on their dyno.

I feel like I’ve researched it pretty well and most people seem to get the tune and headers at the same time so I never really got the answer I was looking for so I’ll just do my own research on my car.

 

Yeah did the titanium tips. For an extra $100 why not?

 

When I ordered mine that’s originally what I bought. Then days later when I noticed it still
never shipped and I paid for 2 day shipping I called and was informed that they were out of stock for the foreseeable future. So I cancelled and ordered from somewhere else that had them listed as in stock and called them to double check availability and was told they didn’t have them either, but the website didn’t reflect the actual current availability. So I canceled that order as well and when nowhere I tried to order from could give me an in stock date because Invidia was closed due to COVID I went ahead and got the stainless steel version. And got it the same week.