Recently had my secondary cats replaced with 2.5" resonators and did some before and after tests with Dragy. Tests were done on exactly the same piece of road, same tune and boost. It was the same Shell v-power 99 Ron pump fuel (93 octane US). The only difference was the secondary cats removed to make the comparison as accurate as possible. I already have VRSF downpipes so was unsure if the gains would be worth it.
2006 E92 335i Auto - Full Weight
Stock turbos
JB4 + Race BEF Map 1 (15 psi)
XHP stage 3
FBO
Stage 1 LPFP
Tests done were 100-200km/h.
With secondary cats: 9.28 and 9.31
Secondary cats removed: 8.94 and 8.96
An improvement of 0.34 seconds. I'll get my car on a dyno soon to confirm.
I have just switched over to E50 and ran 7.72 and will be at the drag strip next week with 170kg (370lbs) removed, so will be able to get a 100-200 comparison.
Calum
2006 E92 335i Auto - Full Weight
Stock turbos
JB4 + Race BEF Map 1 (15 psi)
XHP stage 3
FBO
Stage 1 LPFP
Tests done were 100-200km/h.
With secondary cats: 9.28 and 9.31
Secondary cats removed: 8.94 and 8.96
An improvement of 0.34 seconds. I'll get my car on a dyno soon to confirm.
I have just switched over to E50 and ran 7.72 and will be at the drag strip next week with 170kg (370lbs) removed, so will be able to get a 100-200 comparison.
Calum