Hey I'm looking for anyone who Is or has run the xr1 muffler. What case size did you run/ or recommend running, 12 or 16". I'm going with single 3 in to a single in out xr1. Motor is a 355 mild build 330hp 345trq at wheels. Any advise is appreciated!

 

If both fit, bigger usually is a little quieter and flows more... also weighs more, 14-16" isn't that big a difference either way.

 

Which part numbers are you considering? The XR-1 line is quite extensive. Flow rates from 800 to 1400+ cfm.

 

I'm sorry I meant the 12" or 16".
Part numbers are 40943 and 40944. I've seen a couple pictured on third gens, but no part numbers or lengths posted with pics.

 

Bump for help

 

Calling out those of you with this muffler or have had this muffler in the past.

 

There are several considerations when selecting a muffler. They would be in no particular order: sound, fitment and performance.
I would think that any muffler that fits within the confines occupied by an OEM sized muffler will be fine. Any of the Borla XR-1s should fit. 12" or 16". Any replacement mufflers I've looked up for our cars are under 24" in total length.
Sound is subjective. I've been told again and again that my simple 40 series Flowmaster sounds great. I'll have to say is that it's not particularly loud but it has a nice even tone at idle. The Borla would definitely raise the decibel level...quite a bit. If you want volume, the Borla should provide it in spades. Having said that, I'd love to hear a Borla equipped exhaust in person. I can't say I ever have.
As for performance, the general rule of thumb is that an exhaust system (including the muffler) should provide 2.2 cfm/horsepower before the restriction and resulting backpressure start to limit potential power production. 400 chp requires 880 cfm. Our 3rd gens, using a stock exhaust configuration are limited to a single muffler. That limits our choices.
I haven't found your part numbers or any related flow data on them specifically however the XR-1s look to have plenty of flow potential. Upwards of 800 cfm which would seem to satisfy your (and mine) flow requirements.
I hope that helps somewhat.

 

I haven't listened to these personally and I know that it may not do the XR-1s justice but here a few sound clips I came across.

 

Awesome, I have seen the 1st video before. That one is with a 383 motor, and the 2nd one is a Borla cat back with different muffler. Third I'm sure would always sound good since it's a ls motor.
There is a video out there with a 355 like mine, it's a bit hard to track down. But either way I love the sound from both the first video and then other video I found. If I come across it I'll post it too.

 

Like I said, I'm considering the Borla XR-1 myself so as to get that 800 cfm+ flow however what I don't want is an overbearing sound. Particularly at idle. I start my car at 6am in this new neighbourhood and I don't care to wake the neighbours!
I'm surprised no one has posted their results.

 

I'm just thinking holiday times maybe not as many are logging in. I did a search on here and there are prior post about the muffler, but without to much detail.

 

Bump

 

Bump

 

Single race bullet will be a loud drone ALWAYS I believe. I just added a Dynomax VT muffler to go before my 4" Dynatech race bullet muffler. No more drone, incredible flow rate. Also turbo'd but these muffs are getting pretty good reviews. Goodluck!!!

 

Go 16" to help quiet it down. If no cat it will be loud. My 383 ran the 12" version and it split ears but was amazing in tone

 

Awesome that's exactly what I was looking for

 

Ok sweet, I don't have a cat and I don't wanna be a menace to neighborhood. Lol

 

Was thinking about putting a bullet in the place of the cat what would you guys think

 

Nice to hear someone chime in. I'd like to move up to high flowiung muffler myself and it's good to hear some reviews.

 

Also good to hear.

 

Exactly, thank you guys very much for any and all advise.

 

I'm thinking in going with 16 in case, but I will weld in a provision to add a bullet in where cat once was just in case it is way to loud.