Here's what's next. After 2 years+ of ownership with my BLM, trying so hard to improve its throttle response, now that I came to a solid conclusion after witnessing several GaGa in the attempt of "increase horse power" on a dyno machine.

The stock 4-1 manifold is indeed too short before hitting the catcon. Hence exhaust flow was blocked due to conflict of cylinder purge. Anyone who change their exhaust manifold to after market performance extractor will indeed restore some horse power, we're looking @ about 5-10 wheel horse power! If u have an idea of tuning a normal aspirated engine, each wheel horse power gain is a thousand dollar investment! Have seen most if not all Campro S4PE running on standard extractor below 80whp, some worst below 70whp. Whereas many other S4PE who replaced their extractor to after market had a significant power restored to 80 & above. So far the highest power dyno output I've seen is 95.5whp & 95whp. Both of them are our forum member.

When u ask for decat, the 1st thing in mind is environment & polution. Frankly, I do not encourage removal of catcon. So my next big thing is, after installation of after market performance extractor, I'm going to put back a catcon to see how much power loss after the 5-10whp restoration. If after catcon can still bring me back to 80whp region, I'm more than happy to keep it that way as a tree hugger.

Finally, the significant of 4-2-1 & 4-1 extractor. Sadly, what I believed all these while was partially untruth & no opportunity to make comparison between the 2 evil on a same car(who would wanna have 2 sets of extractor on a same car just to dyno for the truth). Anyway, some comparison was done between similar layout of vehicle with similar mods has been done. So here's the truth, 2 B16A was tested on the same day.

Specimen A) HKS green mushroom with Spoon sausage intake ram, Mugen 4-1, hotbits bullet, 2" piping & Spoon S-flow, yielded 142whp with drastic jump on vtec opening on stock ECU.

Specimen B) Spoon sport drop in filter, TODA 4-2-1, hotbits bullet, 2" piping & Fujitsubo chambered muffler, yielded 143whp with slightly smoother vetc opening on stock ECU.

I have no picture to show u as owners preferred stay anonymous for their security reasons. Anyways, the comparison between the 2 EGs are on the same dyno platform. The result shown 4-1 extractor has less initial power output due to conflict of exhaust purge I believe. However, once rpm raise to 4k, torque curve for 4-1 improved significantly better than 4-2-1 due to straight output with less joints. Whilst 4-2-1 slowly catching up by 6krpm, both car show similar power curve 1 stays @ 142, another @ 143. I wouldn't know whether the chambered muffler has restricted exhaust flow from 4-2-1 or the Spoon S-flow helps on the big jump of vtec gain for 4-1 extractor.

My conclusion is, either way they should yield similar output where 4-1 give much better mid/high end power, whereas 4-2-1 is generally smoother & steady output system. I going to work with 4-2-1 and show u my dyno chart once its done. And the follow up action will be having catcon & decat comparison. Have a good day.