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Discussion Starter #1
What did Lexus do to the IS 300 motor so that it puts out less HP (I belive 10 HP) than the GS 300?

Would it be simple/cheap to get back the lost 10 HP that the GS has?
 

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lexus decided to destroy the enviroment with low fuel milage instead. you have to fill up the tank every 20miles with the is
 

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Originally posted by Risk3233:
What did Lexus do to the IS 300 motor so that it puts out less HP (I belive 10 HP) than the GS 300?
Primarily the stamped/welded exhaust manifold (versus a real header on the GS300) and single-muffler exhaust.

Originally posted by Risk3233:
Would it be simple/cheap to get back the lost 10 HP that the GS has?
Simple, sure. Bolt-on a real header and a less restrictive exhaust. But since all three catalytic converters are integrated into the stamped/welded exhaust manifold and front exhaust pipe assembly, a street-legal header would need to incorporate and be sold with one or more cats. Read: very expensive.
 

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im on here too much. i read almost every post that goes up. i have no life. i am addicted to this forum. i am also addicted to money and tang. and driving. and tang. and posting. and tang. i should really hit the gym more, especially if i want to play football next season. and tang likes smooth abs.
 

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the part of the exhaust that is supposed to be responsible for the hp loss is the header, because of a tighter engine bay. if toyo motos exhaust adds 13hp, but doesn't include header replacement, then you can count on getting more hp with a good header.
 

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Discussion Starter #15
I understand that a cat-back exhaust will at approximately 12-13 hp. Is this true? What would a header with stock exhaust add? What would both a header and exhaust add? If you add a header, do you lose the cats?

Are either the headers or exhausts currently available aftermarket?
 

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FYI: Most headers can add HP, but they tend to be tuned to add it at high RPMs. In some cases you give up some low end torque/hp to get more at the higher RPMs...
 

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make the engine breathe as best as it can, or get headers designed for lowend.
 

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Actually for a low end power you will want high torque at the bottom, which means you cannot have a free flow exhaust. You will need some backpressure to help the compression at the low end. Therefore, you usually see high end horsepower gain on the free flow exhaust rather than low end.
The fact is that exhaust is probably the hardest part to tune if you want one that perform good through out the entire rpm range.
 

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actually, a free flow exhaust would be fine, coupled with the right header setup that would be designed for torque instead of peak power. you can create all the back pressure you need with the right header setup.
 
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