Catback vs full exhaust with racing car for stage 1 ECU tuned DS3 thp 155 - 190bhp

[Sirdan555]

Hi everyone, just looking for advice from anyone who knows more about exhaust mods than I do. I'm going to get a milltek system. I'm not really looking for a massive noise, just a nice one. But the main thing is bhp. I want to get the most out of the stage 1 remap ive had.

I hear the cat on the ds3 is restrictive and I could get significant benefits from a racing car rather than just doing the catback. Clearly this costs a lot and I don't want to do it if the gains are pretty much marginal.

Also, will I need to remap again in either of the scenarios?

Thanks for any advice

Dan

[MrT]

If you go for a cat back you effectively leave the cat in place, so while your new exhaust might gain you 1 - 2 horsepower with a slight more noise , you won't have huge benefits,
Ideally you want to lose the cat and have straight through from turbo back,
This will net you 5- 10 horsepower and bit more noise, now you can get a racing cat put in which are indeed expensive and in essence act like they aren't really there due to being less restrictive,

As for having a remap after, well you might want to get the car retweaked to gain the benefit of the decat and exhaust and to prevent any overboost as this can some times happen in extreme cold weather when you have no restrictions in the exhaust system,
Overboost can occur due to no back pressure which is usually created by the cat.

[Sirdan555]

awesome, thanks for the reply. Sounds like I need a sports cat then. I don't want to go cat-less because it's a bit of concern come MOT time etc (but definetly tempting as a lot cheaper!). Good to know I probably don't HAVE to get ECU remap afterwards (although probably will get it retweaked in future if can get more gains, especially if add cold air intake system in future).

What do you think of this: SSXPE101 on http://millteksport.com/exhaust.prod...?variantid=408

It's a high flow sports cat and downpipe. It mentions needing a stage 2 remap? Is there a reason why its saying stage 2 specifically? As far as I understand the stages of tuning are fairly fluid?? What I've had is technically listed on quantum tuning as being stage 1, but the guy at the tuning shop said no point in going beyond this unless putting hybrid turbo in and bigger intercooler.

Thanks
Dan

[BenS]

Parts manufacturers throw the word "stage" around all the time to make their parts sound cooler, and there is no definitive explanation for what all the numbers mean. A simple assumption would be:

Stage 1: software only e.g. remap, chiptune

Stage 2: external engine bolt-ons e.g. exhaust, intake, intercooler, turbo swap

Stage 3: internal engine mods e.g. forged pistons + rods, different cam profiles, boring out the manifolds or cylinders etc.

This is by no means universal, but makes some sense at least. I swear I've seen companies advertising stage 6... overkill much!

[Sirdan555]

Awesome, that makes a lot of sense!

[MrT]

The biggest difference or benefit you will gain is from losing the restrictive cat. Wether you go for a ful decat or a racing cat with cat back exhaust.. dont expect huge gains as at the end of the day this is only a 1.6..
A propper remap after fitting the exhaust will gain you some bhp and will change the feel of the car.

[Sirdan555]

Thanks a lot. What are your views on upgrading the intercooler? I know the stock one is really small but is this really going to have a big effect on road use, 0-60 blasts and flinging it down country roads? I know heat soak is the issue, but with a 190bhp remap, upgraded exhaust, air intake system, will the intercooler be a serious factor?

[MrT]

Absolutely upgrading the intercooler is a must if you want to A, remap and chase more power and B, to alloy the turbo to sustain the boost longer.
Again our friend the remap rears it s head ..lol
Ok to put in simple terms,,.
Upgrading or fitting a larger intercooler is the easy part, but because the air has larger surface to cover and a bit more pipe , you introduce lag, so with the stock setup a larger intercooler will give you some lag , but if you drive flat out and do some hard runs the turbo will hold boost longer due to more cold air being fed into engine via intercooler, this is why again you will need to have a remap to gain full benefit of the mod,
But the upshot is by fitting a larger intercooler you can run higher boost and for longer duration without loss of power,.
For example , my mates bmw 330d, when we fit a larger fmic, the charge temp dropped by 4 degrees, and after a remap the car made 20 more bhp, plus holds boost longer and further in the rev range...
Hope my ramblings make sense

[Sirdan555]

Awesome, definitely makes sense. Thanks