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mike2002 · 05-02-2005, 04:03 PM

borla is stainless steel, but it is expensive. very few shops bend stainless steel, most have aluminum. the stainless steel pipes are pretty expensive compared to aluminum.

headers dont give you more power because they're 2.5" they give you more power for a few reasons. 1 there are no ridges, it a completly smooth setup. on the stock exhaust manifolds the exhaust comes out and hits a basically 90* wall, and has a very rough path to make its way back to the cat. lots of sharp corners, which is bad for backpressure AND velocity, which is why headers designed correctly give you power through the whole power band.

also, they help from scavanging. if all the pipes come together in circular kind of twist motion, what happens is the exhaust comming out of one cylinder gets to this point right when the next cylinder is venting out, if made correctly (by varying pipe size and length) the exhaust passing through will actually help to suck the exhuast comming out of the next cylinder, THATS what makes a good header(s)

edit: the bigger pipe does help, but its not as significant as its made out to be. you have alot more velocity by the engine then you do at the tailpipe, which is why its more benifical to have bigger pipes at the engine than the end of the exhaust

people are so happy with there 2.5" because they see how big it is and now they can brag to there friends that they have "2.5" catback" for a stock car like mine, intake/exhaust/dhp/pully is the most i had ever planned to get for it, so for me it was more benifical to keep the stock pipe. if your planning on headers, 2.25" is your best bet. you may be able to pick up a used borla kit of here, or grandamgt.com. since its stainless steel it will last forever. the grandam borla kit is dual exhaust, the alero kit was twin tip

05-02-2005, 04:03 PM	#23
mike2002 GLS member Join Date: Aug 2004 Location: rosemount, MN Posts: 1,340	borla is stainless steel, but it is expensive. very few shops bend stainless steel, most have aluminum. the stainless steel pipes are pretty expensive compared to aluminum. headers dont give you more power because they're 2.5" they give you more power for a few reasons. 1 there are no ridges, it a completly smooth setup. on the stock exhaust manifolds the exhaust comes out and hits a basically 90* wall, and has a very rough path to make its way back to the cat. lots of sharp corners, which is bad for backpressure AND velocity, which is why headers designed correctly give you power through the whole power band. also, they help from scavanging. if all the pipes come together in circular kind of twist motion, what happens is the exhaust comming out of one cylinder gets to this point right when the next cylinder is venting out, if made correctly (by varying pipe size and length) the exhaust passing through will actually help to suck the exhuast comming out of the next cylinder, THATS what makes a good header(s) edit: the bigger pipe does help, but its not as significant as its made out to be. you have alot more velocity by the engine then you do at the tailpipe, which is why its more benifical to have bigger pipes at the engine than the end of the exhaust people are so happy with there 2.5" because they see how big it is and now they can brag to there friends that they have "2.5" catback" for a stock car like mine, intake/exhaust/dhp/pully is the most i had ever planned to get for it, so for me it was more benifical to keep the stock pipe. if your planning on headers, 2.25" is your best bet. you may be able to pick up a used borla kit of here, or grandamgt.com. since its stainless steel it will last forever. the grandam borla kit is dual exhaust, the alero kit was twin tip __________________ 2001 Alero GLS - Sold!