E4EVL
Well-Known Member
- Thread starter
- #1
On UK/euro spec cars we have catted downpipes but also secondary cats/OPF which is a bit of a pain. I’ve seen very little posted out there around this as most of the tuning posts come from the US but I’m looking at the idea of a catless downpipe but I don’t know what to do about the secondary’s.
No one at the moment seems to offer a secondary cat replacement pipe as there’s little demand. I don’t want or need a full cat back exhaust system as I quite like the stock sound, it’s not mega restrictive and I’m not spending four figures for nothing so it’s not an option, please don’t even go there.
That said, there are however three potential options on the table as far as hardware is concerned but I don’t know the impact in terms of tune. So...
1. Run a catless downpipe and retain secondary cats (my ideal solution)
2. Run a catless downpipe and have a custom section fabricated to cut out the secondary cats and sleeve it but ultimately easily reversible (ballache)
3. Run a catless downpipe, cut the secondary’s open and smash the internals our, re-weld shut, irreversible (rough tactic!)
Now... option one is the route I want to go down ideally if the feedback I get from tuners supports. I appreciate it will restrict the system somewhat having the secondary cats still in place but if the impact is minimal and it won’t prevent me from running a stage two 93 octane (98 RON) tune then I’m good to go. If we’re talking only talking 1-2% hp/torque impacts then I’ll keep them, if it’s a greater impact I may reassess.
I know Litchfield motorsport here in the UK are offering a stage 2 tune where they cut the secondary cats open, smash the core out and re-weld them shut which yes... it serves a purpose and does the job but when it comes to resale or more importantly MOT time (our annual roadworthy test including emissions), the instant they see that welded up it’s a fail. Yes there are friendly testers out there if you can find them but I can’t be bothered with the aggro. The fact they’ve removed them would suggest better power gains but I’m not going to ask directly as I’ll just get the BS sales pitch.
Long story short, what are the implications if any of running a stage 2 map with decat downpipe but secondary’s still in place?
No one at the moment seems to offer a secondary cat replacement pipe as there’s little demand. I don’t want or need a full cat back exhaust system as I quite like the stock sound, it’s not mega restrictive and I’m not spending four figures for nothing so it’s not an option, please don’t even go there.
That said, there are however three potential options on the table as far as hardware is concerned but I don’t know the impact in terms of tune. So...
1. Run a catless downpipe and retain secondary cats (my ideal solution)
2. Run a catless downpipe and have a custom section fabricated to cut out the secondary cats and sleeve it but ultimately easily reversible (ballache)
3. Run a catless downpipe, cut the secondary’s open and smash the internals our, re-weld shut, irreversible (rough tactic!)
Now... option one is the route I want to go down ideally if the feedback I get from tuners supports. I appreciate it will restrict the system somewhat having the secondary cats still in place but if the impact is minimal and it won’t prevent me from running a stage two 93 octane (98 RON) tune then I’m good to go. If we’re talking only talking 1-2% hp/torque impacts then I’ll keep them, if it’s a greater impact I may reassess.
I know Litchfield motorsport here in the UK are offering a stage 2 tune where they cut the secondary cats open, smash the core out and re-weld them shut which yes... it serves a purpose and does the job but when it comes to resale or more importantly MOT time (our annual roadworthy test including emissions), the instant they see that welded up it’s a fail. Yes there are friendly testers out there if you can find them but I can’t be bothered with the aggro. The fact they’ve removed them would suggest better power gains but I’m not going to ask directly as I’ll just get the BS sales pitch.
Long story short, what are the implications if any of running a stage 2 map with decat downpipe but secondary’s still in place?
Sponsored