exhaust backpressure

[treukauf]

Ok I'll probably be shunned for asking this, lol, but what effect does the removal of the cats have on a 02 5.3 liter. 1Do the rear o2 sensors merely send off a SES code or does the computer attempt to alter its A/F ratio? I'm sure this will get some laughs, but I live in Montana. Eastern montana, on a ranch where the population density is pushing almost 1 people to 50 square miles haha. Its always been a competition to see who has the loudest pickup. and the fords are dominating(very very bad even 5.2 dodge with cat. scares my silver.). They may be slow, but they make my single straight 5.3 sound like a 2 day old kitty. I know nelson can program the rear sensors out, but the funds are currently lacking for a tune. ?2I have heard lots of stories about people loosing back pressure the bottom end power disappearing when they went to dualpipes with mufflers. (also very very bad as i really enjoy 18mpg)Has anyone out there gone to a completely open system with a single stock pipe(2.75in). I would think as long as i don't go to dual 2.5's exhaust velocity will stay up. Just wanted to know if anyone has done this. Cutting off the stock muffler made an amazing difference both in mpg and hp.
P.s. Any other tips for more noise( wow I feel like a two year old, but I can't stand to be beat by fords AND dodges). I was going to try to fabricate a straighter exhaust or go to dual 2 inch. Thanks for any help.

[chrisj6]

If you want the straight through muffler go with Magnaflow, I got the flowmaster just cause I take more of a liking to the sound. I cut the cats on my 99 and made a hell of a difference on the top end, and didnt really lose a whole lot on the bottom end. Allen definately made up for that with the tune! The rear o2's are there only for catalytic efficiency, and have nothing to do with the a/f ratio.

Chris

[TXsilverado]

if you want to be as loud as possible lose the cats and find some good headers. thats probably as loud as it gets. i couldnt imagine running around listening to that!

[TXsilverado]

oh yeah, you can get some o2 simulators to keep that service engine light in check...

[treukauf]

Originally posted by TXsilverado@Mar 20 2005, 11:06 PM
oh yeah, you can get some o2 simulators to keep that service engine light in check...

Where do I get these o2 sims at. I really can live with the check engine light. I can just check my codes regularly, but a cheap sim. would be nice. Not enough mula for headers now. How much gain is felt from some shorty headers, as long tubes would on my 4x4 would get eaten alive by gravel. I ask because the current exhaust manifold is almost header like. I would really like to know if any one is running pure straights as i'm scared to loose tons of bottom end. I was contemplating dual 2 inch to get a crackle from H3LL.

[TXsilverado]

im not too sure where you can get the simulators but theres quite a few people runnin cutouts with gutted cats. someone will speak up.

[1slow01z71]

Do a google search for o2 sims you will find about 20 links. I didnt go dual 2 inch on my 5.3 i went dual 2.5 without the cats or mufflers lost a little bottom end not as much as everyone complains about but it was so un-godly loud my neighbors hated me. But you dont have that problem huh. Dual 2 inch should be fine. Last i looked the sims were running around 20-30 bucks not too bad. Headers will make a difference but IMO i would do the dual 2 inch straight pipe. Thats just about as loud as ur gonna get. Then later if you have the $$$ get a set of shorties. The long tube headers really dont go down far enough to really have a problem with gravel. I have heard the pacesetters are longer than TOG, ASM's and the others so your statement might be true for that set. Do it right someone needs to stick up for the chevy's.

[treukauf]

Thanks for the replies. I really wanted to hear from someone whose done it. I'm going to leave it pure straight with the single 2.75 pipe for now then up grade to dual 2 inch or 2.25 straight out the back. I've heard less bends mean more noise which would also help velocity if the volume of pipe was not too large. I'm cheap, extremely cheap. I think i might cut the cats in half and weld a solid pipe through the center to reduce obstruction and add to the james bond feel of it lol. I still don't think I can beat that 95 351 noise wise. he's got 2.25 dual straights, It barks like 300 german shepards covered in cats. I could write 10 pages on camshaft theory but I really don't know much about the maddness of exhaust noise.

[LS1Nica]

Stailess steel carries sound alot better than cast iron, plus the extra lentgh on LTs give you that race car sound. Since your cheap then I guess gutting the cats its about the only thing you got left. You said you got rid of your muffler? I cant wait to get one cuz when I let off the gas my truck has a nasty sound almost like a damn jetbrake (its a 6speed). Also consider a resonator they actually sound louder than not having a muffler at all. Check with SLP for the simulators and maybe you can customize the their loudmouth exhaust (its loud) to fit your truck.

[RedHeartbeat]

To make it louder be sure you put some megaphone tips on the ends of the pipes. In theory megaphones work awesome. Look how loud it makes them pretty little cheerleaders yell.