Hahaha, I don't have mine anymore... I sold it as soon as I bought this diffuser....
But I do have a feeling the lip might be too narrow for the R34 front bar... Or it might be okay if you don't have a lip like mine, since the lip flares out at the bottom.
Hmmm.. Yeah it too a bit of time as I had to cut into the top of the diffuser to make sure it sits flush under my lip lol. And it definitely doesn't sit too well if you have a return flow front mount, because of the return pipe on the bottom pushes the diffuser down (if that makes sense lol).
Normally the bottom of my return pipe will scrape when going down steep drive ways, with this diffuser covering the bottom of the pipe, the clearance at the front is now probably 50-60mm less than before, because of the tray underneath the diffuser. Gonna be scraping it a lot....