thekevin

I am just going to replace my factory muffler with a borla or magnaflow most likely and leave everything else in the exhaust system stock. I need to get a 3 inch and out muffler correct.

yugnat

Wait till somebody else confirms this but the inlet of the stock muffler I believe is 2.5", as is the resonator pipe going into the inlet of the muffler. That is a bottle neck in the stock catback (how big a deal is up for debate). You might be able to get a muffler shop to modify the resonator pipe to fit a 3" muffler inlet but I'm not sure about that either. The other option would be to either buy or have a muffler shop make a true 3" resonator delete pipe from your down pipes to the 3" muffler inlet giving you a 3" system all the way through. Again, wait till somebody backs me up on all this - I just went ahead and mentioned it all since you said you're about to buy.

thekevin

So you think it's 2.5 in and 3 out.

RACER X

does Borla sell just only the muffler?

thekevin

Yeah, I have put the ProXS on my last two trucks. I normally just order them off Ebay and my local muffler shop normally charges me $25 to swap them out.

RACER X

Thanks, I didn't know that

Maybe I'll have my local shop quote me to run a pipe w that muffler straight out the back w that rectangular tip or maybe 2 tips, like the Roush exhaust

yugnat

That should technically work but if your going through the trouble of modifying I would take advantage and try do do something to get a true 3" all the way through... but that's just me. Are you opposed to deleting the factory resonator? You would then hear the turbo whistle but with the right muffler (large enough) it still wouldn't be too loud.

thekevin

I don't know about getting rid of the resonator. I don't want my truck to sound like a fart going down the road.

thekevin

After listening to a few video's of 3.5's with stock mufflers and no resonator I may just do that. I may switch it over to 3" from the flange to the muffler with no resonator. Does anyone have a video of a 2.7 set up like that.

CitizenMTB

For what it's worth on my 15 F150 5.0 I actually lost performance going to a 3" resonator delete system. What a lot of cat back exhaust manufacturers fail to disclose is the added horsepower (which is even debatable) is at very high RPM's and you actually lose power at lower RPM's. Ended up putting my stock resonator back on to increase back pressure and regain lost performance. In the future I will just save my money and just do a muffler swap.