MK5 Golf GTI
All Things Mk5 => Modifications & Technical Area => Performance Modifications => Topic started by: spwd on December 16, 2016, 03:03:30 pm
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Just wondering if I should get my friendly mechanic to drop the exhaust off and drill the pre- cat out and wondered how louder its going to be?
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Just wondering if I should get my friendly mechanic to drop the exhaust off and drill the pre- cat out and wondered how louder its going to be?
Doesn't really make a lot of difference. It's more going from the standard DP to a 3" one that makes it sound louder.
Make sure he doesn't clog the second cat with crumbs from the first one when he does it!
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Thanks bud, and yeah I'll be sure to tell him :happy2:
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Best to do it upside down on a bench, then all the crumbs fall on the floor and not into the second cat :smiley:
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I'm thinking I might do this soon, is it worth the work involved doing it ie does it make any noticeable difference?
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I'm thinking I might do this soon, is it worth the work involved doing it ie does it make any noticeable difference?
Loads of threads on this - the consensus is that it works nicely with a Stage 1 map. Anything to free up the exhaust is a good thing on a TFSI; that and fuelling are its main bottlenecks.
Stage 2 necessitates a larger downpipe as there's only so much flow the standard downpipe can achieve, regardless of whether the cat(s) have been gutted. I think it's 2.5" diameter or less.
But for a quick, cheap mod to help get the best from a Stage 1 map it's a no-brainer.
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I've been told the cats are the biggest bottlenecks in the system and it doesn't look a hard job, if you have the room to get the downpipe off.
This is one of the cheapest and easiest mods that people do on a Toyota MR2turbo and it sounds like it helps on the golfs, but I'm sure someone more cleverer will be along soon to give you better info, obviously a replacement downpipe is better but I've not got £300 + to spend on that so this is next best thing.
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, looks pretty easy to me :happy2:
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If I go full decat 3" down pipe will it pass an mot?
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If I go full decat 3" down pipe will it pass an mot?
Not with a decat.
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Hi SPWD- I ummed and arred about this too but had it done in the end and all I can see are gains not negatives. Unknowingly I had a cheap after market DP on mine when it went to R-tech for a stage 1 and it hindered the power before and after the re-map. Since then I had the cam chain tensioner done, pick up pipe service, sump off and cleaned, millers nanodrive oil and while they were at it, got AKS to fit an oem DP with the pre cat deleted. All of these things have really sorted the old girl out and I can feel a real difference now. The car used to lurch a bit on pull away but that is now remedied and when you give it the beans the car is more responsive. It isn't really any louder as such but you get a nice burble if you blip the throttle. I'd get it done mate! Cheers, Ollie.
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Cheers Ollie :happy2:
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I noticed no noticeable increase in noise from the Exhaust after removing the Pre-Cat on my Edition 30, It did make 315BHP and 330LB/FT of Torque at R-Tech after the Stage 1 Re-Map though so was a very worthwhile upgrade.
I do recall noticing a Minor increase in Throttle response and less Turbo lag too but I only drove the car for a few days before getting it mapped.
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Thanks for the info bonelorry :happy2:
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No extra noise here too - a few extra pops from DSG shifts but not anything someone would think was from a 1.4 Vauxhall nova with a 6" back box system lol
As others have said more positives and no negatives to report. Get it done :happy2:
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:happy2: :happy2:
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I now have bonelorry's Ed 30. It's not loud at all. Get it done, my friend.
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I now have bonelorry's Ed 30. It's not loud at all. Get it done, my friend.
Will do as soon as I can get a piece of pipe to delete my resonator then I'll ha e my dv replaced and my lowering springs and the pre-cat delete done at the same time :happy2:
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Hi SPWD- I ummed and arred about this too but had it done in the end and all I can see are gains not negatives. Unknowingly I had a cheap after market DP on mine when it went to R-tech for a stage 1 and it hindered the power before and after the re-map. Since then I had the cam chain tensioner done, pick up pipe service, sump off and cleaned, millers nanodrive oil and while they were at it, got AKS to fit an oem DP with the pre cat deleted. All of these things have really sorted the old girl out and I can feel a real difference now. The car used to lurch a bit on pull away but that is now remedied and when you give it the beans the car is more responsive. It isn't really any louder as such but you get a nice burble if you blip the throttle. I'd get it done mate! Cheers, Ollie.
Was the cheap DP a de cat or a sports cat?
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I've been doing some back to back comparisons of standard downpipe, standard downpipe with pre cat removed and an aftermarket 3" DP with sport cat (APR).
I would say don't waste your time with decatting the OEM pipe and go straight to an aftermarket 3 incher. The difference between decatted and catted OEM is so tiny, it's not worth effort imo.
The problem with the OEM pipe isn't so much the pre-cat, but rather the 2.5" bore and the horrific bottle neck where it's crimped to clear the gearbox.