I'm planning on installing LT soon and was looking at Speed Engineering headers and their ORY, I was leaning towards adding cats to cut down on fumes and rasp, I have a vert so those issues may be more noticeable with the top down.

I've searched a bunch of threads and found a few people recommending Magnaflow Spun-cats #59959 installed between the headers and ORY. I couldn't find a definite answer and nothing current.

Is this the best option? How about the Thunderbolt cat? http://performance-curve.com/catalyt...verters/410300

Is it just as simple as adding (2) 3" OD cats, trimming the ORY and bolting on?

Thanks!

 

This ain't rocket science. If you have enough of a straight run of pipe, cut a piece out and weld a cat in. Repeat on the other side.

 

I have the Magnaflow on my Jeep, I had a random technology. Butt dyne says the Random tech unit reved better but was not as quiet.. The random tech style (Metal matrix) radiate a lot of heat, plan for it.. The magna flow has a heat shield and is a ceramic matrix so a couple lbs heavier. But Quieter..

 

Thanks, I understand the process but it's a tight space under there so I figured I'd ask those who've already done it...

Thanks for the info I appreciate it

 

See if there are any slim-profile converters out there, not much thicker than the pipe diameter.

 

Thanks, I'll see what I can find

 

Get TSP headers and the TSP catted Y pipe. That's easier than trying to add cats to a off road Y pipe.

 

Was sold out last I checked, I'm not in a rush, I emailed TSP to see when they'd be back in stock but haven't heard back....

I thought I'd have an easier time getting the LT and Y to fit together by sticking to one brand

 

Forget any Y pipe with cats if your state doesn't require you to have cats. Just read the horror stories on this site about clearance issues. Put a single cat in the location in the intermediate pipe by the passenger rear seat where people typically put the cutout. If you were planning on putting a cutout there, get DMH low profile cutous and weld those into the Y pipe. If this is about quieting it it down, put a Magnaflow 14416 just before each tail pipe and use a magnaflow 12267 if you need it even more quiet in addition to all the above. Magnaflow 12467 if you want the polished version.

 

Thanks, I had read that suggestion too while trying to research this, didn't see many that had done it... That does seem like the better option. I'm just looking to keep the fumes down mainly because I like taking the kids out with the top down and I didn't want them to have to stink like gas.

Thanks for the suggestion, are you running this setup?

 

I'm going to be. My issue stems from the fact that I'm running a short torque arm and I want my SE headers setup to work with the MWC "catback 3.5 Y pipe" cross-member which has excellent clearance for my car that is lowered 1 inch.

The goals for my setup are:

No fuel smell in cabin
No power restriction when cutouts are open
Quiet as possible when cutouts are closed
Excellent clearance when lowered
Must wake the dead when cutouts are open (single cutout in int pipe not enough)
Must work with CME catback setup

After reading info on the various setups, not many have done what I'm about to do because of the expense. The key component is the Y pipe selection. I'm going with the TSP offroad Y because it is proven to have excellent clearance with the SE headers.

Speed Engineering LS1 Longtube Headers 1 7/8
TSP Offroad Y pipe
DMH low profile electric cutouts
Walker 53061 I pipe
Walker 54064 I pipe
Kooks GE-307540 (1 of them)
Magnaflow 12267 or 14267
Magnaflow 14416 (2 of them)
CME Exhaust tips and elbows
6ldesigns valence
Walker 33272 exhaust clamps (6)

That's $2k for the exhaust and valence parts above
$400 in body work to mount and paint the valence
$400 in exhaust cutting, plasma cutting, and welding

So for $2800, one can have a CME exhaust look while having the best of all worlds. Without the CME setup, you are still looking at about $2k

The unknown factor here is can just a single Kooks Cat in the intermediate pipe keep the fumes down enough along with a proper tune. It gets hot enough in the intermediate pipe to activate the cat, but I don't think there is room for 2 of them in series without having clearance issues or rubbing against the 3.5" driveshaft. The other unknown is how restrictive is this exhaust going to be when the cutouts are closed. A cat followed by that magnaflow and then another magnaflow on each tail pipe should quiet it down a lot, but with the cutouts closed its probably going to be down on HP.

Right now my setup is the single cutout in the I pipe, a double drop cross member (which is poor for ground clearance on lowered cars) as it was the only way I could get the SE engineering Y pipe to clear, and a Dynomax, Ultra Flo muffler #17227 (the magnaflow is quieter). With this setup, the car sitting in my driveway and windows up, I'm getting 70db at idle and 80db at 2000 rpm in the cabin with the cutout closed. For comparison, my 2013 honda accord v6 is 45db at idle and 50db at 2000 rpm. The idea is to get the car as close to 45db as possible. I may not need the Magnaflow 14416's if the cat and the Magnaflow 14267 quiets it down enough. Time will tell.