Hi i have the FMF Q4 end can, TM33/34 BB modified pumper carb. BB351 kit.

I'm still running with the stock header.

I was thinking about buying a FMF powerbomb header. But what can one expect in terms of performance upgrade ? Is it just a minor improvement across the range? They can be picked up for around $170. So its kinda expensive.

But don't want the stock header to be a bottle neck to the other upgrades i've done.

 

What I know with a stock bore: With lid removed, mid and top end WOT AFR kept under 13:1, A Megabomb will unleash big power in the mid range and top end..

I would expect the Powerbomb to make noticeably more power everywhere on a 351 , vs the stock header - assuming your Bill Blue TM is set up correctly for proper AFR.. At least proper wide open throttle (WOT) AFR...

 

I noticed significant increase in upper rpm power, but lost quite a bit of snap at low rpm and speed. This was actually a disappointment for me because the bike no longer wheelied by just snapping the throttle at low speed with no clutch. Since you have the 351, obviously you don't have that problem down low so your overall result would be better than mine. One thing to note is that you will lose your heat shield and it will instantaneously melt anything it gets in contact with.

 

On a stock bore, FM is correct. A quick look at my charts shows that the stock header with a slipon will make a far superior TRQ curve below 6.5k than will the Megabomb + PowerCore 4 . I am running the MCM but I am quite sure the same holds true without it. The power unleashed with the full exhaust + rejetting + lid off above 6.5k more than makes up for the loss - top speed well over 90mph, highway passing power, etc ..

None of which applies to a 351 - except that forcing one to pump exhaust through the stock header can't be optimal..

 

there is the clone bomb header pretty cheap too
I use that on my bike

 

Annnnd? Holding up well? Fit was good? Rusting? Which one did you get?

Thinking of one of these too...

 

I did a thread on it when I got it
its stainless steel, so no rusting
fit fine, still using it

I think in the thread I did I posted the measurement to the muffler and where I got it from on ebay