Best downpipes that are not insanely loud?

[JoeSTi]

I just fitted a mbrp catback on my z and it sounds great. Not too loud, no rasp, no drone. Having said that my next mods are downpipes, intake, heat exchanger and tune for the time being. This car is my dd and I dont want it to be super loud. Im ok with it being a little louder than it is now with the mbrp but I dont want rasp and drone. Also I want to keep in mind my future goals with the car which is a 93 octane vrx70b set up. My goal later down the road is 500whp with bigger turbos without e85 since its my dd. Now with that in mind should I go full catted downpipes or just lower resonated downpipes? Im currently eyeballing the boosted 6 resonated lower downpipes but I dont want to buy them and then have to buy full downpipes in 6-12 months when im ready for bigger turbos. With all this being said here are my main questions.
-Do I need full downpipes to hit 500whp on 93oct with the vrx70b turbos or will I be fine with just lowers?
-Are full downpipes a ton louder than just adding lowers?
-What downpipes should i look at for achieving my power goals later and also keeping noise down?

 

[Hernandooo]

-Do I need full downpipes to hit 500whp on 93oct with the vrx70b turbos or will I be fine with just lowers?
Yes
-Are full downpipes a ton louder than just adding lowers?
Yes
-What downpipes should i look at for achieving my power goals later and also keeping noise down?
AMS Performance VR30DDTT Street Full Downpipes

The Loudest being the Catless. These would be your best bet. As for volume, if you want the HP with those turbos, unfortunately, this setup will still be loud, but tolerable

 

[kevinbonds]

I was thinking of going the downpipe route and decided against it for now. Plenty of cars making 440-450 WHP without them. If and when I go the turbo upgrade route, I will just do full downpipes since it will be easy at that time. Just my .02.

 

[sublimehemi]

boosted 6 seem to have a catless but resonated...

 

[FSUZ33]

Sort of on-topic, and curious. The Z has upper and lower DPs. Are they both catted, or just the upper or lower?

 

[JoeSTi]

Sort of on-topic, and curious. The Z has upper and lower DPs. Are they both catted, or just the upper or lower?

There is a cat on each upper and lower.

boosted 6 seem to have a catless but resonated...

Yessir thats the exact one im eyeballing. Im mainly wondering if the top cat on the downpipe is really killing much power or is it the lower?

 

[Hernandooo]

There is a cat on each upper and lower.


Yessir thats the exact one im eyeballing. Im mainly wondering if the top cat on the downpipe is really killing much power or is it the lower?

It's a restrictive point, shares the same catalyst & diameter as the lower, as for how much hp you're leaving on the table, idk

The full down pipes with upgraded catalysts have less restriction compared to just having the stock upper

 

[JoeSTi]

It's a restrictive point, shares the same catalyst & diameter as the lower, as for how much hp you're leaving on the table, idk

The full down pipes with upgraded catalysts have less restriction compared to just having the stock upper

Exactly. I wish someone did a dyno comparison of lower vs full downpipes. If it was 5-10 hp I dont care at all. I would take that hit and do lowers only to keep the sound in check. But if its 30hp now ive got to think about it.

 

[Hernandooo]

Exactly. I wish someone did a dyno comparison of lower vs full downpipes. If it was 5-10 hp I dont care at all. I would take that hit and do lowers only to keep the sound in check. But if its 30hp now ive got to think about it.

It's going to really depend on the tune, I went conservative with 425whp, 19 PSI. I could've gone more (450-475whp) but my main concern was keeping the car reliable

 

[kevinbonds]

It's going to really depend on the tune, I went conservative with 425whp, 19 PSI. I could've gone more (450-475whp) but my main concern was keeping the car reliable

I don't think downpipes really show their magic until you upgrade the turbos. Some cars on just intake and cat back are making around 420hp and 440tq. Beyond that, you are pushing the stock turbos, and they are just over spinning and way out of their efficency zone.

 

[JoeSTi]

I don't think downpipes really show their magic until you upgrade the turbos. Some cars on just intake and cat back are making around 420hp and 440tq. Beyond that, you are pushing the stock turbos, and they are just over spinning and way out of their efficency zone.

This is exactly why I want to upgrade turbos. I would rather put the turbos back into their efficiency range and not create extra heat trying to push small snails too hard. I think the motor would last a lot longer at 500whp with bigger turbos that are happy than with 450whp with smaller turbos that are not happy.

 

[kevinbonds]

This is exactly why I want to upgrade turbos. I would rather put the turbos back into their efficiency range and not create extra heat trying to push small snails too hard. I think the motor would last a lot longer at 500whp with bigger turbos that are happy than with 450whp with smaller turbos that are not happy.

This is exactly right, which is why I am not going to get a LDP, which I had originally planned. I think over time, the cost of the replacement turbo's will come down, and when I get the bug will upgrade the turbo's and do a full DP then. For now, it's just an intake, heat exchanger and a cat back.

 

[Hernandooo]

This is exactly why I want to upgrade turbos. I would rather put the turbos back into their efficiency range and not create extra heat trying to push small snails too hard. I think the motor would last a lot longer at 500whp with bigger turbos that are happy than with 450whp with smaller turbos that are not happy.

They actually do quite a bit. Baseline our cars start at 375-380whp. With my setup (intake, Intercoolers, heat exchanger, dp's and exhaust). Pushed it up to forementioned 425whp, with the torque being on the low end. Again conservative, if I really wanted to could've pushed it past 21 psi on the stock turbos, but I'm not in a rush to blow them up. There are plenty folks with the same setup doing 500whp, just choose not too

Also, eyeing on the vrx60, for the type of driving I do (canyon runs) I find this would be more suitable

 

[5thZ]

If you are not going to upgrade the turbos I'd offer the same opinion as kevinbonds for now. Now, interesting news, CZP is nearing completion of their Garret turbo upgrade kit. Each turbo is rated for 550 HP each.

 

[JoeSTi]

If you are not going to upgrade the turbos I'd offer the same opinion as kevinbonds for now. Now, interesting news, CZP is nearing completion of their Garret turbo upgrade kit. Each turbo is rated for 550 HP each.

Is it going to be a direct replacement kit like the z1 kit? What size turbos? Assuming it will use the stock air to water system?