Spoke to a borla tech today on the phone. Apparently previous info I heard was not completely correct. The borla system will enter productin within several weeks, however the guy said power gains were minimal, less than 5RWHP. The system will be cat-back however, and change the sound. But the tech said it didn't help much because the stock exhaust is already straight pipe and mandrel bent...So much for that. Maybe I will do that pre-silencer mod

 

But hopefully they'll be some weight savings so it's not all bad.. 5hp and a little less weight. =)

What mods do you have on your GS400?

 

Looks like it gonna be a CPU upgrade for me

 

If my previous expirience with the VQ (in my Maxima) proves anything, there will be minimal gains without changing the y-pipe (section before the cat). This will eliminate the precats (my guess is 2--like the Max, and that is what it looked like when I looked). Nissan seems to do a good job on design, and the most restrictive part is emmisions equipment. The good news is, precats only effect the emmisions at start up, when the engine is still cold. I would not recomend removing the cat, but a high-flow cat may help also.

I think the only significant gains will be had with a new y-pipe, high-flow cat and cat back exhuast. Headers made little or NO difference on the Max, and cost a lot. The TS headers that cost almost $2000 seem steep, but I will reserve judgement until I see a dyno, Top Secret seems to make some pretty amazing stuff. The Maxima may not be the best basis of comparision because there is very little aftermarket support for the Max, but my guess is they will be similar.

I also think the same goes for intakes, Nissan did a pretty good job, but a CAI with a full exhaust will yield some good gains. A ECU would help a lot also. The ECU on my Max seemed to show a running rich error quite often because of the exhaust and intake.

One last thing, a y-pipe without precats would be considered for "Off-road use only" and in some states that may cause problems. But, I will have no problems adding a y-pipe, I think it will add the most power. I may even keep the stock catback, The y-pipe, cat and catback on my Max was LOUD, very LOUD. I tried the stock catback, an APEX WS, and a custom one from Courtesy Nissan in Dallas. The stock had a little more sound with the y-pipe, the APEX (which was supposed to be the quitest of the aftermarket), was a lot louded and gained about 5-8 hp, and the Courtesy was extremly loud, but gained about 8-12 hp.

 

notice that the y-pipe does not have pre-cats. Or is that thing on the y junction a precat?

 

and the aftermarket pipe....

 

ooops ...here it is

 

Where is the silencer that the other guy removed to get his exhaust to sound better?

 

 

of the pre muffler. can you get a closer pic. than what you have?

I have seen that on some pics. but not on a car itself. Need more info if you have it .

Thanks

 

I think that is the cat, and the 2 things labeled 3 are the precats. I am not sure, the exhaust is a lot different than the Maxima's, I guess I could raise both and look. The Maxima y-pipe is much different, check out Stillen's site, or Warpspeed performance's website for pics. From what I have been told, Nissan uses precats on all VQ engined cars, for emmisions....

It seems to me there is power to be had by: removing precats, high-flow cat, and a cat back system that is a little straiter (is that a word?), such as a midpipe that goes into the back of the muffler, it seems like you could eliminate that bend going into the muffler. All good 2.5-3" mandrel bent piping. I think stock is 2.5" pipe diameter, three may be a little too big, I know on the Max 3" was too big for N/A (2.25 was stock), although the Z is much more powerful....

 

yeah, what mods???


Doc

 

where is this y-pipe from?

 

Top Secret of Japan
www.topsecretjpn.com