gmore

Just had my oem cats swapped with Magnaflow metallic 200 cell ones (#59976 offset for primary and #59956 straight for 2nd) and so far(all of about 10 miles), am loving it. LSS, didn't want to drastically change the sound but wanted a little more volume, edge and power and had planned on replacing the primaries with a 200 cell and the 2nds with the Vibrant Ultra-Quiet resonator via either custom fab or the Armytrix DP but... the reputable/reasonable exhaust shops in the area will only replace a cat with a cat so opted for the above with the thought that once the work is done, I could swap the 2nd cat with a resonator if I didn't like it and still be money ahead - better to be lucky than good. Obviously still early and I may change my mind after a tune, E85 and time, but really enjoyed what I heard in the cabin on the way home, and it was easy to avoid 'obnoxious' via the throttle once I got into the neighborhood. No CEL yet.

All in I'm at $760 ($360 for cats, $400 labor/SS) and figure I've added somewhere between 15 and 236hp...just a guess

semi-cold start-up video...

Kriston

did you baseline the car before doing the exhaust work? Would be curious to see how much power the M156 makes without LTH but Primary / Secondary cat deleted.

skratch77

I think the ultimate budget build would be to just delete the primary cats and leave the secondary ones in place.

I've done the Mike's power pipe delete and it's not that much louder than stock.

I've also done the armytrix full cat delete pipes and the car is just as loud as full long tube headers.

The biggest sound restriction is the primary cats

gmore

No - have never dyno'd and no monitoring yet. Butt dyno certainly feels quicker but no doubt the added sound helps the overall feel/fun-factor.

Did a ton of research before going forward and best I can recall from reading numerous posts - 2nd-delete add 2-5hp; primary delete add 10-25hp(assuming a hotter tune at 25hp); 200 cell cats deduct 2-4hp. I recall a post comparing straight pipes/stock manifold vs LTH w/tune was somewhere around 25-40hp difference...memory ain't the best, so please correct me if I'm wrong. I strongly considered LTH but didn't want to take a chance on the sub $1500 models and potentially dropping $4K+(install, hi-flow cats and whatever else to tweak/tame the sound) for the added hp on a street car that I have well under $20K in (for now), just didn't work for me. Keeping it 'budget' for now and loving the sound/feel - just need to make up my mind between EC and OE for a tune.

gmore

Yeah - I followed Doc Ocs Armytrix thread where he had logs, Armytrix DP, and Magnaflow 200 cell(a bit farther down from primary location) at a 'way too loud' level and some Armytrix youtube videos helped confirm. I'm sure the logs added some volume as well, but didn't want to just replace the primary and then have to keep adding afterwards to tame - this is why I originally planned to use the Vibrant quiet resonator in place of the 2nd cats (had great results with one on my Subi build and thought the add'l 200 cats might still be too loud). I considered leaving the oem 2nds as well but best info I could find(and could be wrong), are ceramic and at 95K, my oem exhaust had a very noticeable smell at start-up (none since replacement but could be cold weather?) I imagine time/miles added some additional restriction with the oem cats (albeit probably minimal) but figured I'd take them out regardless.

I'm FAR from any kind of exhaust guru (and I mean FAR), but am big into sound/audio and have to believe that the position of the cats(or resonators) plays at least some role in the overall sound(not to mention the oem resonator). I've only heard LTH via video and some set-ups sounded great, but quite a bit different than oem? No doubt different in person and I'm rambling here. At some point in time in the future, I may swap something else for the 2nd cat just to see, but feel pretty certain that anything other than something to reduce sound at that position (all else being oem) would be too loud for me.

SGT-PillzBury

I did a primary and secondary cat delete for $300 at my local exhaust shop. Sounds awesome and still quiet when cruising but when under load and over 50% throttle it sounds awesome and louder than stock but not crazy loud. I love it, only downside is the CEL but I can easily get rid of that when I get a tune.