Had A Exhaust Question

-Alero- · 04-24-2005, 10:51 PM

what if, i went straight piping, from the downpipe back withonly a muffler. this muffler would be the camaro style muffler. any ideas on what exactly this would sound like?

i know straight pipes are illegal, but knox county doesnt do pollution tests. i know of plenty of trucks around here without a cat, and or muffler.

04-25-2005, 12:09 AM

Do it! I did it on my car, and it's really easy and cheap if you know how to weld and use a sawzall. I just bought a section of pipe from Midas for about $10, went to the auto hobby shop on base, cut off the cat and silencer with a sawzall and welded up the straight pipe. Keep one thing in mind. It is easier to weld the top of the pipe (where it is closest to the body of the car) if you have the exhaust removed from the car.

-Alero- · 04-25-2005, 12:17 AM

yeah but what does it sound like, im perfectly capable of mig welding, but i dont know how i'll get a lift, or get the exhaust off.....i need to think more into this. if i wanna do this i wanna do all 2.5 from the downpipe back. or should i start where the cat used to be?

04-25-2005, 01:16 AM

o , thats fast

04-25-2005, 11:58 AM

It does make it a little bit louder. My exhaust sounds a little raspy, but not quite ricey. Yours will probably sound a lot better since you are getting a camaro style muffler. My muffler is kind of like something you would see on an import. I would replace all of the piping with the 2.5" piping. Any muffler shop should be able to easily bend this for you. However, it could get kind of expensive when you get to welding a flange on for the exhaust manifold connection. I would just cut it off between the cat and flange and re-weld the flange onto the piping. It was pretty easy for me because I just replaced a four foot section of piping between the exhaust manifold and the bend that goes over the suspension. Anyway, good luck. Heres a pic of my muffler, so you know what kind of style I'm talking about.

-Alero- · 04-25-2005, 07:39 PM

Quote:

Originally posted by Yomeo@Apr 25 2005, 01:16 AM
o , thats fast

Quoted post

what made you say that?

04-25-2005, 10:08 PM

^^^Yeah, I was wondering the same thing? What are talking about? I think he's talking about our sigs. Alero, I would have to agree with you on the Prelude thing. I have yet to beat any Prelude.

-Alero- · 04-26-2005, 04:50 PM

yeah its B/S.....i was so mad that night. cant wait till i can get a job and a beater and just dump nothing but money into the alero.....all just to beat a damn prelude...

04-26-2005, 05:17 PM

The only one I've ever beaten was one of the newer ones with a auto/slapstick tranny. I don't get it, there's a guy running around with a civic that has B18 v-tec swap and I beat him all the time. Oh well!

-Alero- · 04-26-2005, 07:07 PM

maybe one day when my alero is older and all grown up i'll be able to beat one.

-Alero- · 04-26-2005, 07:10 PM

but anyways!, has anyone else doen this setup? and does anyone think this is a good idea or bad idea?

also, if the stock cat flows better anyways, i wont even notice any sort of gain with it there or not, am i right?

04-26-2005, 08:07 PM

Actually, it seems like the removal of the cat and silencer was the single best mod I made to my car. I've taken my CAI and MAFT off of they car and I feel almost difference at all.

-Alero- · 04-26-2005, 08:27 PM

whats a MAFT?

anybody else have good reviews about this?

also, falero dod you have a 4 cyl or the v6?

mike2002 · 04-30-2005, 05:26 PM

ive seen dyno's of "stock cat" "no cat" and "highflow cat" on the same car. they had a huge article in car craft years ago. with no cat, the car lost significant low end, gaining a little in the higher rpm over stock. highflow cat showed gains across the board.

i wouln't chop your cat off, your car will smell like poop if you do. and when a cops behind you and your car reaks, he may decide to pull you over. and the fine for no cat is over $20,000.

on a near stock car 2.5" is to big. you hear everyone saying you'll loose backpressure, loosing low end. there only half right. you dont need back pressure. what you need is exhaust velocity for low end. the bigger the pipe, the less the velocity. backpressure itself hurts you. all these guys on this board have a big ass pipe with a flowmaster muffler. this is about the worst setup you could have. the pipe is huge so they loose velocity (but also loose backpressure which is good) then the muffler has all these baffles in it giving them more backpressure. the best setup would be a smaller pipe and a muffler with no baffles. that way you drop backpressure, but you still keep exhaust velocity. if want even less back pressure than that, get a highflow cat

i put a strait through magnaflow on my car and it was loud as hell, so i got a 31" thrush glasspack and it quited it down alot, but my exhaust doesn't have 1 baffle in it, so even though i have a smaller pipe than most guys, i have less backpressure than most.

-Alero- · 04-30-2005, 05:37 PM

ok so if you say having a smaller diameter pipe is better than a bigger one, then why not just keeps the stock piping??? since its so much better? 2.5 isnt really that big, thats like saying the SLP exhaust makes you loose horsepower.

im pretty confident i'll keep my cat, but just upgrade the cat back piping, to 2.5 im pretty confident it will be fine with benefits, besides the v6's have a decent amount of low end torque but little to no hiogh end torque, so if anything, the more high end torque the better....

and as for my muffler choice, i wont go Slowmaster again, im gonna try to get that Magnaflow camaro style muffler, for the dual exhaust thing

Spilner521 · 05-01-2005, 04:41 AM

small piping is not necessarily better than bigger piping. you have to get the right size for your engine to maintain decent exhaust gas velocity but still be big enough to have maximum flow at the top end of the rpm band. the stock piping is great for low end, but on the top end it doesnt flow well enough to reduce restriction. and like mike2002 said, you want the least backpressure and restriction, and the most free flowing muffler possible.

i have the 2.4 engine in my car but i have driven a few v6 aleros completely stock and i agree, that engine is full of low end torque. so if i were you, i'd go with full 2.5"piping from the manifold back, high flow cat or no cat at all, and a straight through muffler. and if its too loud for you throw in one or two straight through glasspacks or resonators to quiet it down a touch.

-Alero- · 05-01-2005, 05:26 AM

Quote:

Originally posted by Spilner521@May 1 2005, 04:41 AM
small piping is not necessarily better than bigger piping. you have to get the right size for your engine to maintain decent exhaust gas velocity but still be big enough to have maximum flow at the top end of the rpm band. the stock piping is great for low end, but on the top end it doesnt flow well enough to reduce restriction. and like mike2002 said, you want the least backpressure and restriction, and the most free flowing muffler possible.

i have the 2.4 engine in my car but i have driven a few v6 aleros completely stock and i agree, that engine is full of low end torque. so if i were you, i'd go with full 2.5"piping from the manifold back, high flow cat or no cat at all, and a straight through muffler. and if its too loud for you throw in one or two straight through glasspacks or resonators to quiet it down a touch.

Quoted post

thank you, i plan on doing that, but i am not sure how well the magnaflow muffler flows

mike2002 · 05-01-2005, 05:12 PM

you want dual exhaust or twin tip exhaust? not that it matters for flowing, all the magnaflow mufflers are strait through, no baffles.

2.5" slp will give you more power, your car will have higher peak hp, but it will have less hp in the lower rpms. so it does "add hp" but that doesn't necessarly mean your car is faster. also, the stock muffler is very very restrictive, and the slp one is a strait through design, so you have overall alot less back pressure, but unfortanatly less velocity. like spliner said, you have to find the best pipe size for your application, you can go to big, you can go to small. for a 170hp car, 2.5 is ridiculously big. borla had a better setup with 2.25" mandrel, stock is 2" pressure bent. its my opinion that 2" mandrel bent is the best setup for a near stock car (like ours). but the companies know to sell the kits, people want bigger, the average person putting exhaust on there car will order the kit with the biggest pipe. 2.5" mandrel isn't needed unless you are running forced induction.

i could have upgraded my piping from 2" to 2.25", but for the cost, and the fact that i would be switching out stainless steel that will last forever for aluminum that will rust out in 3 years of snowy weather ( i know because i found out the exhaust on my last car just fell apart, rusted through, 3rd winter with it's aluminum pipe) i decided to keep the stock piping and just elimintate the back pressure by using a strait through muffler (magnalfow) if i want to further reduce my backpressure, i could get a highflow cat.

mike2002 · 05-01-2005, 05:14 PM

so the moral is, big exhaust pipe is only for bragging to other kids in study hall that you have it.

take a gtp for example. alot more time and money has been spent on research and development of performance parts for that car. stock they put out over 300lbs of torque (they are underrated). lightly moddified ( stuff like pully, rockers, intake, dhp other small bolt on's....basically a mid to high 13 second car) they recommend not to go over 2.5". so if they use 2.5" for 300+hp cars, do we need it for our 185hp (after mods) car?

-Alero- · 05-02-2005, 12:52 AM

then why is everyone so much more staisfied, with the 2.5 piping rather than the 2.25?

i know i will go stainless steel. but if you read closely, the borlas exhuast is overpriced and isnt even stainless steel. im pretty confident i will go will custom piping.

but the thing i dont understand is that, if i were to get headers, the header piping is 2.5 so if i were to get 2.25 cat back piping wouldnt that create restriction, than rather having 2.5 overall