Exhaust mods question

Hiya guys,
can you help?

My current mods to my 95 skyline gts25t are high flow panel air filter and 3.5 inch exhaust from the cat back.

I am thinking of connecting exhaust all the way up - getting a front 3 inch pipe and high flow cat - I know that this will give me more top end power via better breathing. But I was wondering what effect this would have on throttle response and low rpm down torque. Am I sacrificing low down torque for top end horsepower because of too little backpressure??? Will off boost driveability suffer? This is what i have been told. Is this true?

Help?!

You would have been fine with a 3 inch system as they are good for about 550hp.

You may loose a slight bit in the under 3,000 rpm range but minimal.

thanx,
have heaps more questions 4 u all

-why does this happen tho? (the drop in low down torque)
-what kind of power and ultimate torque gains can i expect from fitting ---the front pipe and high flow cat?
(currently supposed to be 187kw - 250hp and 295nm)
-will peak power and torque be produced further up in the rev range?
-what kind of effect does this have on fuel economy?
-what other mods can i do to the car without playing around with the boost or the ecu?

Also,

If i rip up the isides of my existing cat wont this have the same effect as fitting a high flow cat and save me some cash?

Hi there. With a turbo back 3 inch exhaust you will be looking at about a 10kw gain (above standard) at the rear wheels. You will sacrifice a very small amount of low end power but trust me it is minimal and worth the mid to top end gain. As far as pulling out your cat is concerned I personally wouldn't do this but it is your choice. A high flow cat is not exactly expensive so my suggestion would be to put a good one in. If you want more power you could get an electronic boost controller and raise the boost a little but it is probably best to fit an intercooler before you start playing with boost levels as you will start to generate a lot of heat. Good Luck with it.

Niall.

I had a 3 " high flow cat on my GTR when it came from Japan. I did a dyno with it on and then gutted it and redynoed it. It made no difference at all. So unless it is blocked you will gain nothing.

RazorGTR is right, adding a high flow cat won't really make any difference. Replacing the stock front pipe will though.

Cool. Does it at all matter that the front pipe and cat are 3' and catback is 3.5'. Does it need to be the same all the way thru?

Nah that doesnt really matter. If the catback system was a lot smaller than the front pipe then you would have restriction problems, but your setup will be fine.

BOOSTD whats the ultimate effect on fuel economy with this kind of mod?
Does it suffer coz the car has to be revved harder to go or does it improve somehow?

Originally posted by BOOSTD
Nah that doesnt really matter. If the catback system was a lot smaller than the front pipe then you would have restriction problems, but your setup will be fine.


dope 180 pics, whered you get em?

Dima R33, fuel economy will suffer a little bit but you have to expect that when you are seeking more power. It won't get too bad until you start raising the boost and upgrading turbos etc.

180driftking, I get my pics from all over the web. I have posted a drift links thread in the Initial D forum. Here it is.

http://www.automotiveforums.com/vbulletin/t108221.html