Has anyone done a larger bore down pipe with sports cat and mated it to the stock exhaust with a reducer?

I'm not a fan of aftermarket exhaust notes but still want to unlock stage 2 potential.

I did it on one of my old cars with spot on success for what I wanted, just wondering if anyone has done it yet to the vrs?

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I don't know a great deal about exhausts, but, I'd say that if you want the gains of a performance exhaust, using the reducer will be not that far off the same as a normal exhaust, as there will be a build up if back pressure around the reduction section, if you want something like you describe I reckon you may be best going to a custom exhaust shop, a good one will design a system for you, with your requirements

You might get help from those that have done the Mods, and do know about exhausts, or their experience with them.

Until they come along, some reading here.

http://briskoda.net/forums/topic/378480-apr-stage-2

I have been toying with stage 2. But after speaking to Lucifer, sports cat is defo recommended rather than decat for my3" cat bk exhaust as the turbos don't like no bk pressure. If I do get a sports cat I will b adding the oil restrictor bolt! 

Am also concerned about wheel spin as the Vrs can wheel spin @70mph if the pedal is floored to overtake. 

I don't know a great deal about exhausts, but, I'd say that if you want the gains of a performance exhaust, using the reducer will be not that far off the same as a normal exhaust, as there will be a build up if back pressure around the reduction section, if you want something like you describe I reckon you may be best going to a custom exhaust shop, a good one will design a system for you, with your requirements

The downpipe and cat are the most restrictive parts of the exhaust. If you were running a huge turbo there would be an argument for a bigger bore cat back, and theoretically it should still add a few hp. But as it stands with the standard 2.25" system and small turbo, anything bigger would be more about noise than gains.

I'm not saying a full system isn't the way to go for absolute gains. But from experience I have found the cat back to add very little on top of a dp & cat upgrade.

I might give it a go and see what happens on the vrs

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Edited 14 February, 201610 yr by aholloway21

I agree the cat is the biggest restriction, however not so sure on the down pipe, as this (i would assume) is the same size as the rest of the exhaust causing the same levels of restriction, so maybe you'd be best off with just a sports cat. Saving the extra expense of a down pipe.

Like I say I'm certianly no expert but that's my opinion

I agree the cat is the biggest restriction, however not so sure on the down pipe, as this (i would assume) is the same size as the rest of the exhaust causing the same levels of restriction, so maybe you'd be best off with just a sports cat. Saving the extra expense of a down pipe.

Like I say I'm certianly no expert but that's my opinion

I'm no expert either, someone much brighter than me tried to explain the theory of this once, it went over me a bit.

The basics as I understood it though:

The cat as standard is restrictive full stop. We all know that.

While increasing the general bore size of an exhaust theoretically "increases flow" it doesn't always work like that. You need to keep up a decent velocity in the exhaust to make sure the gases are pushed through rather than limply work their way down. It was explained to me like a hose pipe without a nozzle on the end. Turn it on and the water flows through and out of the other side slowly. Put your finger over the of the hose and it will spray out with more velocity.

The trick to a good system is lowering the back pressure while ensuring you keep velocity to keep everything moving with speed.

The argument for a bigger downpipe in counter to this comes from pushing as much away from the turbo quickly and into the cat to stop heat build up.

Again, all a bit over my head but it's what I was advised, take it with a pinch of salt though.

I'm looking into the idea of just changing the cat now as you pointed towards. I think all in all its just going to take a bit of trial and error.

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