What’s the cheapest FX impact bigger plenum I could buy?

Without having to butcher your rifle , I’d have to say the kit from FX or possibly the polish plenum if they are still available. I have the polish plenum from the second run he did. Great product, fit and finish were good. But the only thing you get is the plenum. I believe the FX kit comes with other upgrade parts. The plenus that were inserted into the rear gauge hole needed the hole to be drilled out and tapped for better air flow , not to mention having to modify the valve housing ,again for flow. 

Agreed, get the kit from FX, way easier. Btw, don’t own an impact and use the word cheap, they just don’t go together

Get one from the UK, it’s easier than the ones mentioned above. Don’t have to do anything to your gun but screw it on in the reAr block. If you want to add heavier hammer, weight, all that stuff you can but certainly not necessary. Stoti

Stu Wrycraft contact him through Instagram at... fx_airguns_uk_

The kit from FX is probably the best, but make sure you get the newest one. They have upgraded many of the other parts that go along with it. I was not all that happy with the power plenum as it only got me about a 20-30 fps gain. I sent the gun off to Ernest to install all the upgrades they have done since then and he got me about a 160 fps gain! I have also heard great things about Stu Wrycrafts kit and he is a great guy to deal with and very knowledgeable. 

I needed some individual parts for power upgrade, I was searching for parts for weeks, but turned out ordering the original FX PP as a complete kit from a single source was a most economical ending.

So from that kit I already modified/ported the Valve House, lapped/polished the Valve House sealing surface, polished the Valve Rod, made a new peek poppet, polished the Hammer and Valve Springs, installed the rubber ball, when all was done I replaced as a full kit I think toke me about an hour a max. But I like to work with my Impact nice and slow and I enjoy every second of it...my LEGO gun.

I have to admit I didn't like the expense neither (114 euros from Krale the entire PP kit) but the convenience...you do all the power mods at your best convenience and replace at onse.

I don't need that power mod for now but this project was a future proofing if I jump the calibre. I was looking into that external plenum (which btw looks like a donkey d*ck ) as well but that can be done anytime if I still miss out some power.

Why have a $2000 airgun and go cheap. I get it though.

I'd go with the full FX PP kit. You'll get the bigger valve with new rod and seat to match along with a new valve spring and a different valve knob adjuster and a new hammer with the c3 attached to the hammer, plus the bigger plenum. I gained 50 FPS with mine that already had an enlarged port. After that I installed the new slug kit, which gave me another ~ 50 FPS. These two mods allowed me to lower the reg's set point for same power plus additional power for slugs. The prices are steep with FX parts.