De-cat

[martint]

hi guys, need some advice which of one these two de-cats is better, should of bought the tuna a car one weeks a go, but had a money shortage! 1) fensport, mongoose Stainless Steel cat replacement pipe, Straight through silencer 2.0GT 2) tune a car.co.uk straight through de-cat with 3" diametre, depending on application (guess the make this one themselfs) looking for performance and maybe a little more noise... cheers

[GT4 BOOSTER]

the flanges on the tune a car 1 are very thin steel 3 mm roughly ( not stainless either )

it dont come with gaskets and new bolts either.

[Kevstir]

if fensport had listed the mongoose one when i got my tune a car one i would have went for the mongoose , the tune a car is 3" which actually robs a little power as the exhaust on the NA Celicas shouldn't be more than 2.5" , as maleborn1967 says the flanges are mild steel, mines aren't thin flanges but for the money you would expect them to be stainless, after all whats the point in the pipe being stainless as you will have to replace it when the flanges rust away ..

I'm getting a full custom zost made up when i get the spare funds and will be getting them to make a new 2.5" decat ..

Its a good mod though m8 go for it :D

Kev

[Cubic Incubi]

What engines need is low backpressure, but high exhaust stream velocity. A fast-moving but free-flowing gas column in the exhaust helps create a rarefaction or a negative pressure wave behind the exhaust valve as it opens. This vacuum helps scavenge the cylinder of exhaust gas faster and more thoroughly with less pumping losses. An exhaust pipe that is too big in diameter has low backpressure but lower velocity. The low velocity reduces the effectiveness of this scavenging effect, which has the greatest impact on low-end torque.

Low backpressure and high exhaust stream velocity can be achieved by running straight-through free-flowing mufflers and small pipe diameters. The only two exceptions to this are turbocharged engines and engines optimized for large amounts of nitrous oxide. Both of these devices vastly increase the exhaust gas volume and simply need larger pipes to get rid of it all.

For noise and styling for the 3sge, i would go no higher than 2.25" exhaust with 2.5" down pipe. unless you run nitrous, and depending on amount of nitrous, you would run a 3" DP with 2.5" or 2.75 - 3" exhaust - effectively a 3sgte set up.

Most folks put on a larger bore exhaust and think because its noisier its faster, that isnt always the case. you can increase throttle response often sacrificing low down torque for an ability to reach peak power a little higher in the rev range. believe it or not - a stright thru 2" exhaust will probably give better results than an increasee in bore - its the restriction of the baffles that needs addressing for free flowing. you must consider the amount pressure the engine is able to make in the exhaust system, if you make it a stright thru system, do you realy need to up the bore.

[martint]

ok cheers guys, looks like it's the fensport one then....