hello guy's!

i have a 99 grand vitara, chiptuned it and added a K&N in-box airfilter not too long ago.

might have boosted it to 110hp? it's not easy to know, but it sure is quicker now

but now i have started to look at my exhaust, it looks like it needs to be replaced in a not so distant future..

when i dhange it i will go for stainless steel, since it's not that more expensive than rusty steel.

but how big should i use? i guess original is approx. 2", then it whould be nice with a 2.5 or 3"?

will it be mutch louder? will it help my perfomance? or is it a waste of money?

Larger bore exhausts usually show some benefit at high rpm, and disbenefit at low rpm.  As your truck is a diesel, it's safe to assume you take advantage of the high torque at low rpm - a larger bore exhaust will reduce that torque.

that is wery interesting..

i guess it whould be best with original bore then :'(
 usually i cruze in 1500-3000RPM's, stretching it to 3500-4000RPM's when i accelerate.

but i like the torqe down low.

before i installed the chip, the car liked to be used between 2000 and 3000RPM's. it was dead below 2000 and meet the wall at 3200.

i don't know what to do but think i might keep my exhaust at 2"
my car is used every day, normally not with a trailer.

If I remember right there's some Australians that make diesel Suzuki upgrades.  You might want to poke around and find them, I bet they could give you some authoritative answers (no offense IanL).
Maybe the makers of your chip have an opinion on this?

Here in the States it's not uncommon to see guys with big, heavy duty diesel pickups with engines in the 6-7+ litres range with exhausts in the 4-5" range.  They certainly don't loose low end as it's a common enough modification and you see it on all of the new wave of diesel pickup dragsters.  No I'm not kidding, it's a sanctioned event now.

So I'd bet you could go bigger...but I have no clue how much.  At the very least you might consider a high flow muffler like a Magnaflow or something else that's straight through.  We did that on our gas GV and noticed an improvement in performance.  It also sounds a lot meaner too.

Yes,  you can go bigger and gain torq and hp. I have 2.5" from the turbo all the way back and noticed a faily big gain from the old 2". Diesel motors do not work off back pressure like gas motors do. Now you wouldn't want the 5" stuff like the 1 ton trucks have but you will sure notice a power gain across the board with 2.5 or 3".

it's a company in Norway that makes custom exhausts, stainless steel.
i will consider to give them a call.
will it help to install a race kat as well? i dont want to remove the kat, as this is a dayly driwer.

i tryed to register at an australian board, but got a reply: invalid e-m|removethispart|@il adress........

I removed my cat, it just restricts flow. Mine is my daily driver.

Eh, the invalid address probably just means their system doesn't recognize your email provider.  Consider a Yahoo or Hotmail account, just about universally accepted.

If you're going for high flow exhaust a high flow cat is always an improvement.  However I must say that here in the States at least, cars made in the last 10 years or so have pretty high flowing cats when new.  So high flow cats don't make much of a difference on newer vehicles when compared to older vehicles with old tech brick type cats.  Then again, if you're replacing your cat anyways, why not use the high flow one?
Modern cats restrict flow very little, and depending on your automotive laws, is against the law.

Definately ask the guys who sold you the stuff.  When they make a recommendation on size ask why they say that just to make sure they aren't simply trying to get you to buy their exhaust or pay them to bend one up.

the cat looks good, but i hawent looked that good at it.

shall take the 100' scervice tomorrow, must inspect it then.

  Diesel motors do not work off back pressure like gas motors do. 

Common misconception about gas motors needing backpressure. A motor is just a pump, be it a diesel or gas powered pump. How does backpressure make a pump work better? Simple...it doesn't but what you don't want to do is to go so big in exhaust dia. that you lose exhaust gas velocity as that is when you will find yourself losing power.

For the Suzuki i would suggest that a 2.5" is going to be pretty good and a 3" is the max and even then it may be overkill as I haven't done any calculations, just going off past experience of similar size engines.

exhaust velocity, my best friends father has a 520+bhp Volvo 740.

he putted on some clothing (like asbestos, don't remember what it's called) on the manifold and after the torbo.
to keep down the heat under the hood.
he said that the clothing also improved the exhaust velocity.

do you think it's true?

will this have any effect at all on a 110+hp car?

Eh, I wouldn't bother beyond maybe some of that header wrap tape stuff on your manifold maybe.  At "normal" levels you'll be best served by gains in your intake and exhaust.  You've done the intake and the chip, so do the exhaust and I bet you'll see a noted improvement.
Then it's time for the dyno.

OK, think of it like this. As the gases cool they slow down so the further down the exhaust the cooler they get and therefore the slower. By expanding the exhaust further down the exhaust as some people do they are slowing down the exhaust gases even further. In actual fact you could reduce the tailpipe dia. slightly compared to the rest of the system to keep the gas velocity up. Think of a hose with water coming out. If the size of the hose is increased the same amount of water will still come out but it now comes out with less pressure. By wrapping the exhaust he has kept the heat into it and that keeps the velocity up. This helps with cylinder scavenging and helps to draw through the fresh charge to help fill the cylinder for the next burn. If you can get a better fill in the cylinder you get more power which is what a blower does on a bigger scale. The downside to wrapping is that it can cause corrosion to steel pipes.

Dyno's are a great tool and good gains can be found in the right handsand should be used more but the $$$ seem to scare people away.

Yeah.  You seem to have to find them at the right time.  Don't know about Norway or Oz but here in the States there are sometimes "dyno days" or club runs where shops let a specific club have their members come in and dyno their vehicles or they just have a special on dyno runs for that day.  It's usually cheaper and at the very least lets you know what you're making.