Gap on the spark plug.
 

I regap my Denso Iridium spark plug from standard .44 to .35, now my car early rpm feels better. And overall the power band of the car improved......does the gap on the spark plug really make that much difference. Does anyone have the same experience?

Yep. I drove the IK20 with 0.032 and they're definitely better than with 0.04
 

When I pulled my stock Bosch plugs out, they we're at 0.028 believe it or not. I just changed to Bosch Super F7LTCR today. The idle and the response is better than the Denso's for the 1.8T. They are the ones with the 3 electrodes, so no need for re-gaping on them I guess. I hear the IK20's are probably a better choice for the 2.8 .

I spent 2 hours last nite reading all the archives on spark plugs...
 

My conclusion is that the IK20 with the .044 gap (factory set) might be ok for a stock 1.8T but is too wide for a chipped car - esp when you push the rpms/boost. It appears that most people have better luck with a .028 - .035 gap.

With that said, most of the S4 guys run the IK22, which is factory gapped at .034, and is one heat range colder. Neuspeed recommends this plug with any Stage 1 upgrade (i.e., chip). I will probably install the IK22s in the next few months.

Chris

Re: I spent 2 hours last nite reading all the archives on spark plugs...
 

I will try the IK22 next time when I change my plug.

If you were changing spark plugs, which ones would be the best to change to?
 

At the gap of 0.035?

Yes the gap does make a huge difference.
 

If the gap is too far apart the spark will blow out during high boost levels. This is why the spark plug is set at .040 for a "stock" A4 1.8t running 7-8 psi. For a chipped 1.8t you want to set the gap between .032-.036, I run all of my plugs at .034. If you plan on pushing the car very hard most of the time, you want to go with a standard copper plug.

Now depending on the cylinder temps and what the plug looks like after a bit of use, you want to go with either a standard temp plug or drop down to a plug that is 1 step colder.

I'd definitely go with Bosch F7LTCR. Way better choice for a chipped 1.8T.