Thinking about deleting my cats. Who else has done it?

[paul_driver]

Lets start off, I don't care about being emission compliant thats for tree hugers. (Already have a full cat back) This coming June I'm deleting my EGR and putting on a Volant cold air intake and having my truck tuned at the local performance/fab shop. Also putting on 275/70/18 terra grappler g2 on which is 33x11. I'm not going to do shorty style headers because headers give you more performance at the top end because of the back pressure. I never drive my truck over 2500 rpm's plus I don't want it to be supper loud going down the highway next year. (driving to collage every day and its my daily driver and I tow daily) I'm trying to get maximum flow in and out to get good highway mpg. I hope theres some guys on there have have done it and can give some input. Thanks!

[dkjbama]

I cut them off my '98 when I was about your age. NEVER AGAIN. The truck had dual flowmasters. It went from somewhat loud to obnoxiously loud. It set a check engine light that wouldn't go away. Gas mileage went from bad to horrible (but gas was about $1.00/gallon then). I was just glad I kept the cats because I ended up getting them welded back on about a year later.

 

Unless your cats are plugged, they're not slowing you down or hurting mileage.

 

If you're looking to save fuel, upsized all-terrain tires aren't going to help either. I went down that road as well, and it led to about 12 or 13 mpg on the highway.

[xXZ-71Xx]

Hi flow cats?

[OregonASEMASTERTECH]

Ok, here is the scoop on cats... as an Oregon DEQ repair shop, legally we can't cut them off.... but most importantly, when you do, the engines back pressure is calculated by the converters. When you remove/cut out or knock the guts out, your truck will run like crap. I had a dodge truck come in and he wanted to remove his cats and install dual 2 1/2" pipes... I told him not to go bigger than 2 1/4.. but he didn't want to listen. So I did as he wanted. When he started the truck, it sounded good... but really loud. When he left the parking lot, he couldn't even scratch the tires. He immediately came back and started accusing me of doing something to his truck. I told him that I did nothing and he was 15 feet away from me when I did the exhaust. I told him that the truck needed back pressure and 2 1/4" pipes is what he needed. He reluctantly said, go for it. After putting the new 2 1/4" pipes on, he started it up, put it in gear and mashed the pedal.... it smoked the tires off! He shut ur down, came back to me, apologized and repaid me for the new tails.

 

THIS is why they make cat back systems! Not only is it legality, but if you remove the cats... your truck will run like shi_.

 

BTW, ALL factory and aftermarket cats ARE ALL READY HIGH FLOW CATS do not buy high flow cats stated on ebay... yours are already there.

 

If you want performance, replace the stock air filter with a AFE pro dry filter.. save the hundreds buying a "cold air" kit. they are actually hot air kits. The original air box pulls air from the inner fender. Plus the pro-dry is a lifetime NON oiling filter. NO RECHARGE kits to buy,

 

Then get a Magnaflow mufflers on it... straight through design, no baffles like the flowmaster mouse and cheese maze mufflers. Then after the intake side is done as well as the exhaust side.. then get a Bullydog programmer. That's it... DONE... DO not buy one of those $20.00 ebay programmers that go on your airbox. They are a resister on the air temp sensor making your truck think it's -40 degrees below zero,, dumping raw fuel into your truck wasting the converters!!

 

Filter $60

Maganflow$200

Programmer $400

Total: about $700 and no headaches!

 

Good luck...

 

Exhaust/auto mechanic/owner for 30+ years

[HARD CORE]

I've done this for many years , I remove cats on all my V8's ... And run long tube headers with as large diameter exhaust as possible and the best CAI I CAN GET ... An LS tuner can make you car / truck run better than ever ! The exhaust will be louder . And inspection stickers are then $100 bucks , and ya better have a inspection sticker connection first .as it will not pass .

[DwayneJ]

Lots of very bad info from someone who genuinely thinks he knows something.

 

First an engine needing backpressure is a myth, if smaller pipe improves lowend it is because the smaller pipe is allowing the exhaust pulse to move faster and pull more freshair in behind it. Air and exhaust have weight and inertia and elasticity and oressure vaves or in this case the VACCUUM the exhaust pulse can leave behind it can inprove performance. This is the exact opposite of backpressure.

 

It is possible to change an engines tuning needs as well, this could cause poor running some of which could improve as the pcm uses the O2s to relearn fueling.

 

That said the 1970s blues brothers "get rid of the cats" mentality is just as bad. Cats haven't been a performance problem since at least the early to mid 90s.

 

The stock truck manifolds are decent for low rpm, the stock airbox is good but the tube can use some improvement.

 

I would scrap your plan and consider a basic dropin cam from someone like CamMotion can make for far more real gains for similar cost to your poor plan and will work fine with stock airbox and stock exhaust manifolds and cats.

 

All that said I have a vehicle with no cats but it is also modified to the tune of 500hp up from the OEM delivered 200hp.......

[vettelovralexand]

You dont need them but it isnt like just cutting them off will make the truck a rocket. Do it for the sound, not the performance. If you plan on doing big upgrades you can still have a high flow set with headers.

[WilliamBos]

Hi flow cats?

The GM cats have been high flow since they went VORTEC back in 1996.

[xXZ-71Xx]

The GM cats have been high flow since they went VORTEC back in 1996.

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