Modified Mongoose...side exit exhaust system

[sammyhale22]

Got my mate to make a custom system for my car. We modified the current mongoose system that my previous owner bodged on... we removed the ridiculously large mongoose tail section and had the exhaust coming out the side of the car just in front of the passenger side rear wheel, very similar to the new chevvy corvettes.
I still don`t know whether this is true... but my mechanic says removing the back box will have no effect on performance at all, just the sound, i.e. i will not lose power or gain power.
I`m going to do a RS Tuner run soon and send the data to Henk to see what effect it has had on torque/bhp if any....
I read that removing restriction from the end of an exhaust system will improve scavenging as the pressure will be alot lower compared to the high pressure build up before the cat. Having a tail pipe cancels out the scavenging as the pressure builds up again at the tail pipe.
Anyone any thoughts or can anyone add to this?

Cheers,

Samuel

 

[OLR]

It will be loud as hell !!

 

[Nick172Cup]

The Mk1 boys love there side exits! I don't think i've ever seen or heard a side exit on a Mk2! Get it done with videos.

The only thing i'd do is have reasonably large centre box to give you some back pressure, because if you take the cat out there will be no back pressure what so ever and will probably run like s**t!

 

[sammyhale22]

I still have the cat in. It doesn`t actually sound that loud if you leave the cat in as i have done because the mongoose system does have a centre section, it sounds deep and burbly. Its when you remove the cat it sounds terrible. Its weird, because the exhaust makes that thumping sound almost like a scooby when im driving along slowly, suppose its because its the same displacement. At 5000-6000rpm under load it sounds gorgeous, very race car ish.
I dunno what it has done to my back pressure, it doesnt really feel any different from before...however i am going to get Henk to read my data log to see if it has made any difference!

 

[Dave..]

Doubt it'll make any difference performance wise.

If you look down the centre of a catalytic converter, you can see why a decat will give you gains. Removing a scilencer will just give you more noise.

 

[sammyhale22]

In theory removing a cat does not give you any significant gain, mainly because an exhaust system has to consist of high and low pressures, unless the engine is tuned specially for the system e.g. a race engine.
The best setup is high pressure just after the exhaust manifold e.g. cat or centre box and low pressure at the exit of the exhaust e.g. high flow back box or no backbox, this high/low pressure produces a vacuum which draws the exhaust gases from the engine out of the system, some call it scavenging. Removing the cat reduces the scavenging effect, it does improve torque but at the cost of power higher up the rev range.