Another Custom Exhaust advice needed.

[DavidPIL]

Hey all...Need several levels of advice here. My MPGs have gone down nearly 5mpg on ave for highway driving, noticing the sulfur type smell on heavy throttle. I'm nearing the 80,000 mark so possibly getting a warranty replacement on the Cat is possible. I got an estimate for a new exhaust. Magnaflow High-flow Cat + Dual exhaust Flowmaster Muffler (camaro?) at $400 while using my existing pipes or near $600 to upsize all the piping to 2.5". Here're the questions... I have a GT, should I... 1. Go all out and upsize to 2.5"?2. Just replace the Cat and Muffler?3. Just replace the Muffler, with the possibility of removing the Cat later?The shop won't do the work minus the Cat but they first off recommended just replacing the Muffler for now but if anything, the cat is the issue. They also mentioned upsizing may cause a slight issue with backpressure (as mentioned here many times). I know about the 2 different cats as well though I think keeping the first (then maybe gutting it in time) is the only option at this time.I know there have been many posts on variations of these questions but with a few years of experience under people's belts and having specific options, what do you, the Vibe experts, recommend?Dave

[tcam]

I had a conversation about pipe size the other day, and from what I understand any larger than 2.5" on an N/A car is just too much and willl result in losing back pressure. So, I'd say go for it. It'd sound reeaaallly good. If you had some type of forced induction, then you would still be ok at sizes larger than 2.5"

[CAN-AWD-VIBE]

get that cat done under warranty if you can. replace the muffler for now. replace the cat and piping later. Or do it all and screw warranty on the cat.dual is a waste of money, weight and space. The vibe will see NO benifit of dual exhaust... except it looks cool. And please dont do it for that and that alone. Seen too many cars with "fake" second mufflers and tips and it make me sad.

[BlueCrush]

I would get the cat replaced under warranty then order a Magnaflow Cat-back from Brad @ http://www.neverenoughauto.com for $379 and install it yourself. It is a direct fit and bolts right up.http://www.neverenoughauto.com...=1685

[CAN-AWD-VIBE]

i like that idea even better then mine.

[GrayFox]

Another problem you might not have considered is the body-work needed on your rear bumper for the dual exhaust.Go with the flow, man... Magnaflow that is

[tcam]

Quote, originally posted by ANO_Vibe »Another problem you might not have considered is the body-work needed on your rear bumper for the dual exhaust. rksport sells a bumper that works with dual exhaust I'm pretty sure

[Mrizzle05]

Quote, originally posted by tcam »rksport sells a bumper that works with dual exhaust I'm pretty sureNo, they "advertise" it but dont sell it.sorry.When i had my dual exhasut on my cavalier they just carefully made a cutout on the stock bumper that matched the existing one.I think Nitrovibegt had dual cutouts.

[drunkenmaxx]

madbill made his own, search and ye shall find

[BlueCrush]

There were a couple people with dual exhaust on here and on MO.OT: What happened to madbill? He also modified his stock springs and had 10" corvette wheels on his Vibe. His Vibe was also known as "BigFoot".

[DavidPIL]

Thanks for all the advice... Quote, originally posted by tcam »I had a conversation about pipe size the other day, and from what I understand any larger than 2.5" on an N/A car is just too much and willl result in losing back pressure. So, I'd say go for it. It'd sound reeaaallly good. If you had some type of forced induction, then you would still be ok at sizes larger than 2.5"I think this place only uses those ripple bend pipes, not mandrel bends so I'm thinking even 2.5" pipes won't be quite as free-flowing. I'm really leaning this way.Quote, originally posted by CAN-AWD-VIBE »get that cat done under warranty if you can. replace the muffler for now. replace the cat and piping later. Or do it all and screw warranty on the cat.dual is a waste of money, weight and space. The vibe will see NO benifit of dual exhaust... except it looks cool. And please dont do it for that and that alone. Seen too many cars with "fake" second mufflers and tips and it make me sad. I'm going to get a High Flow cat which I've read is a bit better than the OEM cat which GM will put in, right? THe Dual exhaust only costs $30 more. It's a Camaro muffler with 1 in and 2 outs so it doesn't really add much more weight and the output won't be a "fake" output. It will be direct from the Muffler.My assumption with the 1 in 2 out mufflers is that most reduce the size of the outputs. Like if it were 2.5" in, it may be 2 - 2" outs. DOn't know if that means anything but some here (including me) have spent more than $30 for a "look" and this would be somewhat functional. I think the Dual out muffler is what I want. Cutting the lower bumper fascia shouldn't be to difficult of a task.Quote, originally posted by BlueCrush »I would get the cat replaced under warranty then order a Magnaflow Cat-back from Brad @ http://www.neverenoughauto.com for $379 and install it yourself. It is a direct fit and bolts right up.I would love to go this direction and was what I was going to consider until I got the estimate for a High Flow Cat and Dual out Muffler. $21 more for a High Flow Cat and the Dual out look is really looking good to me.Once again, thanks for all the advice. If anyone else has anything to add, I'd greatly appreciate the input.Dave