I already have a NM box on my car.

If you had to choose 1 - downpipe or tune?

Toss the NM and do a real tune...or add a DP to what I have. It is a manual.

Thanks!

 

I'm not an expert, but I do believe you need a tune with a catless downpipe. Go with a catted dp if you must.

Obligatory rant - running catless is bad business.

 

There is a secondary cat on the f56.

 

DP first, you need the supporting mods to be able to handle the tune

 

DP is not a substitute for a tune, its a support mod. Even a stage 1 tune with bone stock car will be a huge difference over NM. If you want real power, you want a stage 2 tune with full bolt ons.

 

I was once in the same situation. The downpipe is more or less useless without a tune. You'll just end up with a louder car and a pesky CEL. Stay safe and consult Byetronik for a stage 1 tune. This will be a HUGE improvement over the NM box.

 

Secondary cat is not monitored. Primary cat is, and will throw a CEL without a tune that addresses that particular problem. Catless DP is a supporting mod for a tune, and will add nothing but noise without said tune.