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View Full Version : Cats for 305?


the moose
03-07-2006, 01:52 PM
i know there are tons of posts on this, but theyre all for 350s and stuff. im running a 305, dynomax 12 inch bullet, exhaust dumped before the axle.

i plan on putting on heddman headers and would like to cut my cats off to get more volume... will i lose anything by cutting the cat off and welding in a straight pipe? should i just go with 3inch pipe to match the rest of my exhaust?

a couple of baffles have already come loose inside the cat so im sure its not helping things.

i drive mostly on road, but would like to start doing some offroad. nothing crazy but some mud and trails and stuff. putting on a 3inch BL 2inch blocks and 315/75/16s too... its a z71 reg cab stepside. thanks in advance guys.
the moose
03-07-2006, 01:54 PM
oh yeah, and its a TBI and i made an open element filter for it (cut off all the extra metal from the stock peices.... came out really nice actually)
JJhomer83
03-08-2006, 07:28 PM
oh yeah, and its a TBI and i made an open element filter for it (cut off all the extra metal from the stock peices.... came out really nice actually)

I have a 1991 305. I took of the cat and run the stock manifold with a glasspack. It runs fine for me but mine is just a daily driver
bigolblackie
03-09-2006, 07:04 AM
The exhaust system is the same,either for a 350 or 305, I cant see the difference.:windowlic
the moose
03-09-2006, 11:13 AM
The exhaust system is the same,either for a 350 or 305, I cant see the difference.:windowlic

i just thought maybe the 305 would need more backpressure because its smaller so it might put out less exhaust??
phatchevy06
03-09-2006, 11:36 AM
Most the people I've talked to that have 305's have gotton rid of their cats. They tell me it performs better overall...:D
diadora516
03-09-2006, 12:32 PM
Most the people I've talked to that have 305's have gotton rid of their cats. They tell me it performs better overall...:D

:word: the cats our cats with suck period. i cut mine off, but i plan on putting dual magnaflow cats on. its up to you but i would just put some cats on there and possibly save money (if you are caught its a hefty fine)
phatchevy06
03-09-2006, 12:36 PM
:word: the cats our cats with suck period. i cut mine off, but i plan on putting dual magnaflow cats on. its up to you but i would just put some cats on there and possibly save money (if you are caught its a hefty fine)

:word: I read an article the other day in Sport Truck magazine talking about how the Magnaflow High-Flow cats flowed so much more CFMs then a stock GM converter and how their prob. the best high-flows out there...
the moose
03-09-2006, 04:25 PM
ok so the cat is going . now just to decide on if i want a magnaflow hi flow. or a straight pipe....

i was just on Summit, and the only magnaflow stuff i could find was either universal or direct fit, none of them said hi flow or anything. is that still the hi flow or what?
bigolblackie
03-10-2006, 10:30 AM
Just get the Magnaflow cats,they are better then stock no matter what. When I bought my cats I didnt care what brand,the guy sold me Magnaflows and I believe they are ALL! hi flowing.:mexsmoke:
FlareSide
03-10-2006, 10:46 AM
Running without a cat is definitly the way to go if you want noise. I've heard a few trucks with all straight pipe or highflow cats and they are LOUD. Any aftermarket cat has got to be better that a stock cat though. Is your factory cat monolith or pellet style?
the moose
03-10-2006, 11:14 AM
Running without a cat is definitly the way to go if you want noise. I've heard a few trucks with all straight pipe or highflow cats and they are LOUD. Any aftermarket cat has got to be better that a stock cat though. Is your factory cat monolith or pellet style?

beats the hell out of me... all i know is its got 160k miles on it and it sounds like junk is falling appart in it... thanks to my bullet the exhaust still sounds good, but im going to go with a magnaflow. thanks guys
bigolblackie
03-10-2006, 03:08 PM
What I wanna know is,you people who are cutting your cats off.What do you guys do,when its time to sell your truck Heaven forbid,if you needed money. I wouldnt wanna buy a truck unless all the parts to make it pass the safty are on it allready,otherwise I will want to pay less money for it. :judge: :dunce:
the moose
03-10-2006, 04:05 PM
What I wanna know is,you people who are cutting your cats off.What do you guys do,when its time to sell your truck Heaven forbid,if you needed money. I wouldnt wanna buy a truck unless all the parts to make it pass the safty are on it allready,otherwise I will want to pay less money for it. :judge: :dunce:


thats a good point, but im going to be keeping this truck forever... its old enough that its not worht selling it anyway... couldnt get more then 4k for this around where im from. so i may as well enjoy it.

also, its not hard to clamp a cat on it either. just chop out a section of pipe, slip the cat on and clamp 'er on down.