AVO downpipe, has anyone changed it?

[FMS01]

The AVO downpipe as fitted to my stage 3 kitted NA6 looks a little restrictive, I was wondering if anyone has changed theirs to something else? Perhaps a seperated gasses design like BEGI kits?



Cheers,
Julian

[Okibi]

I know MX52NV has on his NA6, I know other club members in W.A. who have replaced theirs with custom downpipes.

[FMS01]

any idea whether there was any gain in doing it? power/torque/driveability wise? Would any of those guys care to comment? perhaps cost as well?

Cheers,
Julian

[d-mag]

I'm switching from an AVO dump to a custom made dump in the coming months, I'll let you know how it goes. My impressions might not be too useful for you as I'm going from 2.5" to 3" exhaust at the same time.

[Adam_NAclubman]

Not happy with the 2.5? I'm just about to get the exhaust made for mine

[d-mag]

The 2.5" is fine, it makes a good noise, the car makes good power etc. but I just took a 3" exhaust with a race cat and a Varex off my other car and It's just sitting here ATM, so I'm going to use parts of that to make a new exhaust for the 5 (actually, I won't, the exhaust dude will ).

[mx52nv]

The 2.5" is fine, it makes a good noise, the car makes good power...

Agreed.

I have a custom 2.5" dump pipe with the seperation for the wastegate in the dump.
Works fine to over 200rwkw but it is not a race car ...yet.

Les

[Adam_NAclubman]

Cool, I'll go with 2.5 for mine then

[bark]

Julian, you will need a split dump pipe design otherwise when you start to up boost the wastegate gases will not be able to escape and thus will cause your boost to actually increase further and become unstable to tune. I just went through a modification process with my father-in-laws turbo MX5 as he had purchased a dump pipe that was too restrictive. Even after the modification of inserting a separate pipe for the wastegate boost still wasn't able to escape fast enough but at least it was stable to tune with. The wastegate is set at 10psi but because of poor dump pipe design it actually hits 14psi!

Try to run the wastegate pipe as far down the dump pipe as you can as per the pic you have inserted.

[Sean]

any idea whether there was any gain in doing it? power/torque/driveability wise? Would any of those guys care to comment? perhaps cost as well?

Cheers,
Julian

Definately a gain if you are using double digit boost. The AVO unit is a bit of a bottle neck. It does look relatively ractory though...

[FMS01]

Hmm, I don't think it looks factory, I doubt the factory would position the turbo in such a place that the downpipe winds up looking like that.
My default boost is 10psi and my eboost is programmed to do 12 and 14.3 as well. Even if it was the same power and I just got less lag that'd be great.

Julian

[Sean]

Hmm, I don't think it looks factory, I doubt the factory would position the turbo in such a place that the downpipe winds up looking like that.
My default boost is 10psi and my eboost is programmed to do 12 and 14.3 as well. Even if it was the same power and I just got less lag that'd be great.

Julian

In my experieince you'll definately make more power with a custom dump pipe that's a bit larger, I had the little ledge that comes off the firewall modified to give more room to fit a bigger dump pipe so I could get a few sensors into easily. When I put the new engine in and limited the boost back to 14psi we fitted the avo dump for its looks - Regardless of the shape, the case look gets must less attention when boys in blue look under the bonnet, plus I was about to sell the car, and thought the avo piece looked a bit neater - personal preference I guess.