| ZManTN |
Sep 9, 2022 11:12 AM |
Update: I had the high flow Flowmasters cats installed yesteday. These are 200 cell race cats and they absolutely woke the sound of my exhaust right the eff up. I wanted to just summarize my experience on my whole exhaust set up because I have learned a lot since day one and I really hope it helps someone else in the future. There's a lot to be learned about HF cats too. I was debating on 400 cell and 200 cell for some time and in hindsight, I probably should've gone with the 400 cell because they might not have been as loud as my 200 cell cats. I'm totally fine with my 200 cell but dang they are very, very loud. I know the stock cats are 400 cell and so it didn't make sense to me that going to 400 cell HF cats would really make a difference in sound. I learned however that HF 400 cell cats would actually increase sound volume over 400 cell stock cats because the HF ones are shorter and bigger in diameter than 400 cell stock cats. I didn't take that into consideration before I bought the 200 cell HF cats. Another thing is that I had the o2 sensors installed after the HF cats but just before the x-pipe (now also welded on). 30 miles since yesterday with lots of hard driving and NO check engine lights! I am impressed about that.
Anyway, to sum it up, I bought my mustang bone stock and the first exhaust upgrade I made was adding flowmaster flowfx axlebacks on an otherwise totally stock exhaust. They did amplify the stock sound pretty good and made a nice deep tone but it was not very loud. I would say 2-3 on a 5 scale sound meter. Months later, I installed a Pypes x-pipe (clamped on) and that replaced my factory h-pipe. It actually seemed to quiet down my flowmaster flowfx axlebacks a tad so I would say a solid 2 out of 5 at that point and to be honest, I was disappointed about the sound reduction so I decided to replace my Flowmaster Flowfx axlebacks with C&L muffler deletes thinking they would add more volume. With the C&Ls installed later on, the sound changed again and this time with the x-pipe and C&Ls combined on stock headers and stock cats, the sound volume increase back to a solid 3 but only under wot. They were a solid 2 under normal driving and again that was a disappointment for me. I also wanted to mention that the Pypes x-pipe clamp on is not ideal. I installed it myself and was meticulous with seating them on the factory piping and they still leaked at a couple different spots. I just could not fix it with the clamps. Since installing the HF cats though, I did have the x-pipe welded on at the cats but not at the rear because they weren't leaking at the rear factory clamps.
Now jump ahead to today, I had my Flowmaster high flow 200 cell race cats installed yesterday and o2 bungs installed after them just before the x-pipe. My sound volume is AT LEAST a solid 5 and that is no exaggeration. Those HF cates cranked my sound volume waaaaay up and it's exactly what I was looking for. It's actually a tad bit too loud from 2000 - 2700 rpm LOL. I would even say they are level 6 in that specific rpm range. So at the end of the day, my exhaust set up is stock headers > Flowmaster high flow cats > Pypes x-pipe > C&L muffler deletes. I suppose I could install those Flowmaster Flowfx axlebacks again to maybe tone it down to a 4-5 sound volume but right now I don't plan on it.
ALSO, right after the cats were installed, I absolutely noticed a low-end power loss in torque. I am waiting for Lito to get back to me with the intention of restoring 'some' of that low-end power but also optimizing top end power. If he can only restore 30-50%, of that low end power loss, I'm fine with that for now because I plan on upgrading my cams to a low-mid range power band increase set by end of year anyway.
I hope that helps anyone in the future. Here's a video link of my current exhaust note with the HF cats:
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