G35 High Flow Cats And Test Pipe
You'll understand a lot better when you pull your cats out. I was pretty amazed how heavy and clunky they are... almost like sticking a big-*** cork in the exhaust pipe.
The way to go is a true dual cat-back exhaust AND HFC's/ test pipes... It makes a serious difference.
The way to go is a true dual cat-back exhaust AND HFC's/ test pipes... It makes a serious difference.
Just pick up a used exhaust if you don't have the money for a new one...
Yeah, I understand that the cats are very restrictive/dense... I'm not all too familiar with the G35 exhaust set up yet (noob to the Gs 
). But you know, closer to the exhaust valves you are in the system, the hotter the exhaust, so I would think the further it gets away and cools off (and then expands) you would want the piping to get progressively bigger, and so I was thinking that if HFCs for the Gs have bigger inner diameters than OEM, and then you go from let's say a 3" HFC to a 2.25" catback section, it would be a restriction in the system.
But, if the cat honeycombs are a much bigger impediment to flow than just sheer diameter, that would make sense.
). But you know, closer to the exhaust valves you are in the system, the hotter the exhaust, so I would think the further it gets away and cools off (and then expands) you would want the piping to get progressively bigger, and so I was thinking that if HFCs for the Gs have bigger inner diameters than OEM, and then you go from let's say a 3" HFC to a 2.25" catback section, it would be a restriction in the system.But, if the cat honeycombs are a much bigger impediment to flow than just sheer diameter, that would make sense.
also depends on material inside the oem cat, i assume it's quite restrictive, but haven't seen it yet.
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I got 03 sedan with test pipes and a coupe mid with no muffler exhaust wise. Test pipes since they have no resonator they make a raspy sound. I know high flow cats don't do that. So I kinda wanna switch. But my question is wouldn't test pipes give your more hp and flow then high flow cats? If so I would rather save up for cat back exhaust if that would take the rasp away?? Ps. Just upgrading cats in general with a intake "350z z tube with pop charger" you will feel a difference!
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I know this is kinda old but oh well. Just so everyone knows, freeing up more air flow on either side will only provide a small increase in power (on G35's), not the huge gains most people expect or hope for. Breather mods make a much larger difference on FI applications than NA. On NA cars, a certain amount of backpressure from the exhaust side is necessary to retain low end power, so, that being said, these exhaust mods might make for a small amount of top end increase, but they could lose just as much on the bottom.
I know this is kinda old but oh well. Just so everyone knows, freeing up more air flow on either side will only provide a small increase in power (on G35's), not the huge gains most people expect or hope for. Breather mods make a much larger difference on FI applications than NA. On NA cars, a certain amount of backpressure from the exhaust side is necessary to retain low end power, so, that being said, these exhaust mods might make for a small amount of top end increase, but they could lose just as much on the bottom.
Gary
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