The Promise of the VTEC - Exh Header Swap

As some of you may have picked up from other threads, I got a set of non-cat 5Gen headers ('99) with the intention of replacing the stock cat headers on my '04 VFR. I already have Scorpion slip-ons, a Turbo City fpr, aftermarket air filter, PCIIIusb, and have done the flapper mod on the airbox. The bike runs great with the current map, waaaay better than stock, but I had to try the next step available to me (without opening the engine), so I wanted to see how the bike would run with the bigger 5 gen headers and no cat.
Firstly, despite what is written from hearsay, THEY DO FIT - perfectly. But all the hardware from the '99 headers must be there - exhaust gasket, clamps, and, most importantly, the set of down tubes for the rear exhaust - the 6th Gen headers are smaller in diameter and no parts interchange.
The install was somewhat difficult as the set of tubes to the rear exhaust ports are tough to get at. But the whole deal took me ~ 2 hours (including removal the bodywork). The only glich is there is no stop for the centerstand. But, by rotating the lower exhaust clamp blot it can be made to function as a stop. It's working.
Now for the test ride, and this is why I call this thread The Promise of the VTEC. Before, even with the Scorpions, I could barely hear the engine note. I can hear it now . The sound is cleaner and throatier. The cat apparently mutes the note a great deal. The engine pulls much more readily in the first three gears anywhere from 2500 rpm all the way up. It will wheelie on demand! The midrange is much fatter and the torque curver feels flatter - no dips and no 5k rpm hesitation. All in all a much more flexible powerband.
Now the VTEC - zowee. Seat of the pants dyno says a 10% stronger power rush from 8-10 k rpm. Feels like a liter bike (and I've ridden some).
Overall the readiness of the engine to pull and the topend rush of the VTEC makes me feel like I've done a big-bore kit job.
With all these mods I now have a totally different performing bike than stock.:biggrin:

 

Thanks for the write up. I just wish I could find a set cheap and try this myself.

 

Me Too! I have been meaning to stop by the local bike junk yard; this might be the excuse I have been looking for. Not much chance of the right VFR being there but you never know until you look. Thanks again for the write up.

 

Sounds like a cool mod. Well done.

 

has anyone heard of or looked in to Motad downpipes? it is a UK company with a distributor here in the US. they say you can get 5% increase in power and have stock outlet tube dimintions so any half pipe that fits the stock downpipes will fit on the Motad. i have an 02, with Staintune half pipe that i plan on trying the Motad on!

 

Great write up! I almost wish I had a Gen 6...not? I did order a Micron pipe for the Gen 5 though.....I hope I have the same results.

 

I felt the same way when I added the K&N and PClll, My VFR feels like a different bike now, much more stronger...

 

RW, have you had your bike on the dyno after the PCIII? Just wondering. I have thought about the PC but don't know if I should spend anymore money this year on the VFR. My VFR had the K&N installed when I bought it. So I guess that gave it a little more power. I hope with the pipe it will be even better.

 

Here is some specs on the before and after. Before 104.8 HP and 57.6 on the torque, After 109.5 :whoo: and 59.6 for torque

 

Sepp,

This is awesome. Exactly what I hoped to do to my Gen6 VFR. After reading this, I'm going to order all the exhaust parts from Honda and get started.

Did you have to custom-fab anything, or did you just bolt on the 99 headers etc.? I'm particularly worried about attaching the tubes for the hi mount exhaust in the '05 - did that work fine?

Any insight would sure be helpful,

Thanks
Karsten.

 

Stock '98-'99 headers do indeed bolt right onto any '02+ VTEC VFR. The stock mufflers and up-pipe bolt right up no problems. So do aftermarket slipons intended for a VTEC.

The only thing you need to bodge slightly is the centrestand stop.

Some have installed a longer clamp bolt above the centerstand and fitted that with some sort of stopper.

Anyhow, it's not that difficult to figure something out for the centerstand stop.

 

ive seen this mod done alot on 6th gens.but really wanna see the to torque curve.would hate to spend 1500 2000 on mods that did little or worse yet had a negative effect.the dyno sheet post here was that for a 6th gen or a 5th gen?

 

That Dyno sheet is for a 5th gen, PClll is worth every penny :thumb: It would have the same dramatic effects for a 6g as it did for my 5g with the right map...

 

Damn you guys, :hungry: and to think before I read this I was happy with my ride. Now I need a power commander, and a 5th Gen header, and oh the pain it never ends..:yo:

thanks for exploring stuff I would never have the stones :hail: to try! I'm still going to have my Ex-Svc Mgr do it... the more things change...

 

i can see were the powercommandor will help.but what i really wanna see is the before and after dyno of the 5th gen header swap.ive priced it and its not gonna be cheap.just wish someone who has done it would spend a little time and get the sheets done.but more than just the hp gaind wanna see what happens to the torque curve.if it put a big dead spot in the power band or is only a top end mod would like to know.

 

Folks,

I may be a bit exhaust-challenged, but a couple of last questions.

I can see how the 99 headers would bolt on with the right gaskets and other hardware.

The question I have is did the 99 have some kind of connector from where the headers connect to the catalytic converter? Also, does the outlet of that connector pipe end up at the right spot for the underseat 6th gen exhaust tubes (or the Staintunes I'm about to buy) to connect to it?

Sorry for all the questions,

Karsten.

 

The '98-'99 VFR800 did not have a catalytic converter at all.
The '00-'01 VFR800 did.

And yes, the outlet pipe is in the right location for either stock or aftermarket 6th gen exhaust systems.

 

so is there any difference in buying the '98, '99 vs. the '00, '01?

 

Just called Honda in Marina Del Rey. They estimate that '99 headers + collector will come in around $500-600. Seems reasonable given the staintunes will cost me more than that.

I'll be giving this a try. While I was on the phone, I ordered one of the Givi 'spoiler' windscreens with the lip, so I'll let y'all know how good it is when it comes.

Karsten.

 

Oh yes, absolutely.

You do NOT want the '00-'01 headers. They have smaller diameter headpipes and have the catalytic converter.

'98-'99 headers have larger diameter tubes, with NO catalytic converter.

Here's a pic of my '99 headers Jet-Hot coated:



The red circled area is only a collector, NOT a CatCon.

The 2000, 2001s have their converter in this area and are a totally different arrangement for piping.

NON-CAT 1998-1999 headers:


2000-2001 headers WITH CAT: