To the OP, don't get motordyne manifold if you want peak HP by the way. It falls off in the upper rpms vs stock manifold.

 

Again must be 2.25 pipes not manifold, There were only gains, everywhere. About 10hp/10tq midrange, 3hp or so on top
The only one mod I have done and lost HP was R2C intakes.

 

I guess I should have just asked "Which exhaust should I get?"

It sounds like if I plan to keep it NA I should get 2.25inch exhaust. And 2.5 might be good for high-end HP but have less torque? By NA I mean intake and catback exhaust only. No header change.

I think in the end either one would be good, I am not a professional racer or anything and spend most of my time below 5000 rpms so maybe 2.25" fast intentions is what I should get.

I welcome any opinions of my post.

 

On the Fast Intentions website what's the difference between resonator and non-resonator? The price is the same, I assume the resonator reduces rasp is that right?

 

The larger diameter pipes should deepen the tone somewhat. That, and since you have the coupe instead of the sedan... I recommend the 2.5" tubing. Most aftermarket catbacks will be 2.5" anyway.

Yes, resonators reduce rasp and mellows out the sound.

 

Tony from Motordyne wrote a very nice piece with regards to exhaust diameter piping for test pipes, y-pipe primaries, and exhaust.

https://motordyneengineering.com/sca...pressure-myth/

Quote:
"The next experiment took place at the mid-pipe. The mid-pipe was varied in diameter to 2.50”, 3.00” and a fully open Y-Pipe. The dyno testing showed that there was no scavenging effect possible after the Y-pipe. There was nothing to gain from the smaller diameter. The only thing that had any effect was simple back pressure. Using an open Y-pipe as the baseline the 3.00″ single exhaust had no effect on TQ and had only a small 1.5 HP decrease. The 2.50″ mid-pipe slightly reduced TQ and was approximately 4 HP lower than the open Y-pipe."

 

^^ That's a good read, Panda.

Here's a related question/comment. Looking at Fast Intentions website today, their high-flow cats and test-pipes are all made with 2.5" tubing. However, way back in 2014, when I bought my RHFCs from Fast Intentions, I distinctly recall having the option between 2.25" and 2.5"... just like you still have that same diameter option for the catback pipes on the Sedan. At the time my cats were the first mod to the exhaust, matched up with the OEM catback. So I ordered the 2.25" pipes. A year later I went with their 2.5" catback. The flanges from the catback matched up properly with the flanges from the cats, but the piping was 1/4" different. That discrepancy always bugged me, wondering if things were right or wrong.

Looking at the components today in the context of that write-up from Motordyne, I'd say things worked out well. It certainly sounds amazing, no doubt about that.

 

Is there any exhaust that is cheaper than Fast Intentions that doesn't sound raspy and cheap?

 

Went from not caring of looks and sound to it matters after all.
If you don't really plan on replacing the cats you will not make that much of hp difference within the systems themselves as that is the bottleneck.
Have you thought of maybe some axle backs.
I think manzo is probably the cheaper alternative. But in your case I would be comparing stillen vs invidia which I wouldn't go with stillen. The horsepower to money ratio in this platform is a bit pricey compared to others.

 

Yes you are right, I guess I had a lot to learn when I made my first post.

Since I am in CA I don't want to bother with smog issues so cat back is what I am considering. So a cat back exhaust won't really do anything for me performance wise? No way in heck I am going to replace the exhaust to make it sound different. If I replace it I want a performance benefit, but if the cat is a bottleneck so that a cat back exhaust won't make a difference I am not going to waste the money.

 

You should be a bit more clearer in your next threads as once you introduce all of the info from the many options you realize ONE does actually care more than what we admit. It looks like you want the BEST: Price/Sound/ Performance out of a dual exit.

This should help filter some of the responses.

 

Check out SOHO's dual exhaust. I think they are priced very well.
$1050 without their y pipe and $1650 with their y pipe
I personal heard this system on a friend's car and i think it sounds good. He had it paired with ISR headers and Megan Racing y pipe. He has since replaced the Megan Racing y pipe with HBP resonated y pipe to deepen the sound even more.

https://sohomotorsports.com/products...27677259399248

 

Yes, first I thought I just wanted the best performance, but I was not considering a single-exit exhaust. Well, I guess I don't want one of those. And I also thought "Well I guess I don't want a screaming fart can even if it performs well"

So it looks like a decent cat back exhaust is going to be 1000-1500 basically.

 

Yes and the worst part is that most of these systems are not put together properly for that price.

You'll see many folks experimenting with different resonators and mufflers to obtain the sound they want but by then it's too late.

You should look into a thread going around here that has a off shelf put together exahust by combining resonators and mufflers from a shop. I believe this will be your best option.

You wont have the "Shiny look" but this way you save some money and you get as close as possible to a great sounding exhaust.

 

I've always felt that if I were to have a shop customize an exhaust, I'd do it with as many resonators as could fit, and Borla mufflers out the back.