lulululululul New Member 6 Member For: 6y 8m 24d Posted 04/07/17 02:23 AM Share Posted 04/07/17 02:23 AM Hi guys, New to the forum, usually a lurker but I have a question which I have done some research about but I'm not 100% sure about. I have a fg xr6t with supporting mods making 470rwhp. However the car drones way too much at highway speeds even though I have a cat, mid muffler and rear muffler. Recently I replaced the rear muffler with the stock 3 inch muffler. I assume ive lost power but would this be a substantial loss?. Doing some research suggests that it shouldn't harm the engine. I prefer the quiet sound while cruising around. I have a varex on the way which ill probably install but if the stock muffler does the job is it worth putting a 3.5inch varex rear muffler?. Tl;dr - Is it okay to have an exhaust go from 3.5inch turbo back to 3 inch even with power upgrades. Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,238 Member For: 15y 11m 18d Gender: Male Location: Melbourne Posted 04/07/17 02:34 AM Share Posted 04/07/17 02:34 AM It's fine to have it like that. You've probably lost a few ponies, though. Only one way to find out - before and after dyno runs in the same conditions. Link to comment Share on other sites More sharing options...
lulululululul New Member 6 Member For: 6y 8m 24d Posted 04/07/17 02:48 AM Author Share Posted 04/07/17 02:48 AM Hmm that is a good point. Might have to do that. I usually read that getting a turbo back exhaust would require a retune. But if im replacing the rear muffler to a 3 inch would that require a retune?. If I use the varex which is a 3.5 inch muffler I assume that I wouldnt need a tune again at all as its back to what it originally was?. Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,238 Member For: 15y 11m 18d Gender: Male Location: Melbourne Posted 04/07/17 02:50 AM Share Posted 04/07/17 02:50 AM changing the rear muffler (or the middle muffler) does NOT require a retune. It's the cat that is the most restrictive part and if you free up that restriction it can overboost with the stock turbo setup. A varex is totally fine to just install. Link to comment Share on other sites More sharing options...
lulululululul New Member 6 Member For: 6y 8m 24d Posted 04/07/17 02:53 AM Author Share Posted 04/07/17 02:53 AM Cool Cool. Thanks heaps mate. 1 Link to comment Share on other sites More sharing options...
lulululululul New Member 6 Member For: 6y 8m 24d Posted 26/07/17 09:30 AM Author Share Posted 26/07/17 09:30 AM Sorry for reviving this thread but hopefully someone answers. I just had a 3.5 inch varex installed onto my 3.5 inch exhaust with 4 inch dump. The exhaust shop however added some tips to the rear muffler that is only 3 inch in diameter. I am wondering will this hinder performance or be bad for the car?. The guy at the shop reckons it wouldnt make a difference but I am looking at getting more power soon. Thanks in advance Link to comment Share on other sites More sharing options...
Puffwagon Puff Gold Donating Members 15,044 Member For: 9y 1m 28d Gender: Male Location: South Australia Posted 26/07/17 10:14 AM Share Posted 26/07/17 10:14 AM 42 minutes ago, lulululululul said: The exhaust shop however added some tips to the rear muffler that is only 3 inch in diameter. The grammar says muffler but the context says tips. Which is it? Link to comment Share on other sites More sharing options...
lulululululul New Member 6 Member For: 6y 8m 24d Posted 26/07/17 02:13 PM Author Share Posted 26/07/17 02:13 PM The rear muffler is 3.5 inch but I had another tip installed to this 3.5 inch rear muffler. I wanted the tip to be minimum 3.5 inches but they installed a 3 inch tip. Hopefully that makes sense. Cheers Link to comment Share on other sites More sharing options...
Puffwagon Puff Gold Donating Members 15,044 Member For: 9y 1m 28d Gender: Male Location: South Australia Posted 26/07/17 02:42 PM Share Posted 26/07/17 02:42 PM Yep it makes sense. After the exhaust gas goes through the cat and various exhaust bends I doubt a 3 inch tip will be a restriction. As hamster balls said the only way to know for sure will be a dyno comparison but that's a waste of money. If it bothers you then swap it. Link to comment Share on other sites More sharing options...
lulululululul New Member 6 Member For: 6y 8m 24d Posted 27/07/17 02:38 AM Author Share Posted 27/07/17 02:38 AM Cheers mate will leave it for now then. Once I go for the e85 I'll have a look at it again. Link to comment Share on other sites More sharing options...
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