First Mod for a GTS25t

[Myth33]

Hi all, this is my first post here. I've finally ditched my turbo VL commodre and bought a 94 R33 GTS25t (auto).

I really want to do just one or two little mods on my car and was wondering where would be the best place to start. I was thinking about a full 3" Mandrel bent exhaust with dump pipe, hi flow cat etc. I have been quoted $1200 from an exhaust place, is this a good place to start?

And I also would like to know the difference between Stainless steel exhausts and regular bent steel ones?

Can anyone tell me the noise difference. Also should the car be dyno'd or re-tuned in any other way if I do this mod, because I don't want to have ruff idling etc. (Reliability is important to me)

thx in advance

[chaos]

Stainless are more shiny:p

it mainly depends on weather u want power cosmetic or sound system but u find exhaust is usually one of the first mods people do if they have a stocko one on

[chaos]

noise would depend on the muffler and weather u had a silencer put on or not and also on the size of the piping under the car

[Elithrar]

For $1200, you should be able to buy a brand-name exhaust such as an APEXi (N1) or a HKS stainless cat-back system (inc. fitting).

APEXi also makes a titanium cat-back system; its major benefit is reduced weight ($1400 inc. fitting). Coupled with a good quality high-flow cat (say, $300?), you should receive quite a substantial boost throughout the rev range, and you will find that the car performs better both on- and off-boost.

Also, look at getting a 'pod' filter; cheap ones (still good!) go for around $80 all up, and brand name ones can go from $200 and up (HKS, APEX'i, Blitz). A boost controller may also be a worthwhile investment ($200 for a Turbosmart), as you can increase the boost and therefore the performance of your car. An extra 3-4 psi will give good gains; anymore depends on the engine.

Note: The prices above are just rough estimates. Buying it all from the one shop (where possible) might net you a little discount.

[rob77]

To give you an idea I gained 18kw @ wheels from changing to a apexi n1 cat back system from the stock exhaust. With any car, turbo's particularly, the first thing to change is the thing that restricts the exhaust gas flow the most, namely the exhaust. Put a good system on and when you do things like increase the boost you will gain more HP than if you left the stock exhaust on.

[Myth33]

Thx for the advice 'rob' and 'elithrar'. Its comforting when different people can agree on the same things . So Apexi cat back with a hi-flow cat seems like the way to go.

So I'm assuming the 3"dump pipe makes very little difference then, or not as much as Hi-flow cat plus a good cat back system?

As far as the noise is concerned is it very loud? I mean street legal?

[nitemare5]

I dont think investing in a pod filter is as good as/cheap as a good panel replacement (like a k&n replacement)

[Steve]

Cat back, highflow cat (better to get a decat pipe) but make sure it flows well, ie, its big. I have seen a couple of 3" 'highflow cats, that had the same size face as a stock one.

Front pipe, definately worth while. It will give you more off boost and quicker spool up, less lag - its all good.

The dump itself, also worth doing. Try and get a split wastegate type. Probably doesnt make alot of difference with being split vs integrated with the stock turbo, but if you ever want to upgrade, it will make alot of difference.

With the above mods, you will probably find boost has also increased to around 7/9psi vs the stock 5/7psi. If you get a bleed or boost controller, dont take boost past 10-11psi without doing the intercooler first.

[Myth33]

I have just read in the forrums about Iridium spark plugs. Are they a worthwhile thing to invest in even if I only have an exhaust mod? And what is the gap that I need to get?

[Steve]

Dont worry about iridiums, not worth the money. Copper plugs do a good job at a fraction of the price.

I had iridiums, whilst on the dyno changed to coppers, and the performance actually improved, but most importantly, detonation levels measured by the power fc dropped.

[Myth33]

Thx for the reply 'Steve'. So should I ask for any copper plugs? What about the gap?

[benm]

I dont think investing in a pod filter is as good as/cheap as a good panel replacement (like a k&n replacement)

I too would most certainly agree with this.

No point removing your standard airbox (and filter element) to change to a Pod because the Pod is just going to sit in your engine bay and suck in hot dirty air. The standard airbox has a fantastic snorkel on it designed to suck in clean cold air from outside of your engine bay.

Simply remove the standard filter element and put in a K&N worth about $110. It will take you longer to pay for the filter at a shop than it will to change it and you get instant power.

A good thread to read over is:

http://www.skylinesaustralia.com/forums/sh...read.php?t=9292

[Steve]

NGK BCPR6ES gapped to 0.8mm should do the trick.