Hi Guys, I am new to the engine rebuild scene and I have some questions. It has recently hit me in the head to rebuild my engine with WOssner pistons, ZRP rods and ARP bolt and increase the rpm to 8.5k. A set of Catcams 288/280 and decatted midpipe + backbox. My issue is, do I need a rebuild if I am going N/A? I will never boost the S54, it is just not my thing, but I do want to find its limits on a road-going vehicle. So here is what my concerns are. - My engine is going strong at 160k km (about 100k miles) no oil leeks, no excess vibration, the map on the engine is not right (I am not in the UK) and sometimes I can feel it not operating at its highest, but still, no physical evidence of any extreme wear. So what will I really get from a rebuild on an engine which quiet frankly, does not need one? Which leads me to my next concerns: - What will a rebuild with forged internals do for an N/A engine? It will probably rev faster, but the truth is the OEM rods and pistons are pretty freaking light and pretty strong, so will there be any noticable difference? - What power can I expect? Is 400 HP unrealistic? Will I need titanium rods to get there, or Arrow Precision ones for which I will need to sell my organs or start selling drugs for that matter? - I am currently removing the filter system which feeds exhaust air back into the engine and my car is getting decated, 63mm dual pipes and a new backbox as we speak (I do not live in the UK so I can do that hehe), so if I get +15-20 bhp (370) how much more can I expect from a rebuild? - Leaving the horsepower away, what are the benefits? Will the car FEEL 10x better, in terms of the engine pulling better across the powerband? Is it a worthwile thing to do at all on an N/A s54? - Will increasing the rev limiter ot 8.5k be fine? And if yes, can I expect more than 400 hp? - What would anyone who has a tuned s54 suggest? Should I just get an Airbox, De-strain my exhaust (which I already am doing) and focus on lowering the weight or does touching the engine make the car better, not just in terms of BHP, but also feel. - Has anyone used Catcams? They are a lot cheaper then SCHRICK, because I will not need to change the rockers, and they supposedly provide camshafts for some rally teams, but I have not heard of them much before, so any ideas? The car is a daily, mind you, and it gets an occassional track day or hill-climb day. What are my goals? I want to build a better car from the e46 than the 997 GT3 (sounds weird, I know) and I want a very unique car, that just feels a lot better then the stock M3. Think of it as a M3 CSR (the fun/manual CSL). Well, achieving my goals in terms of the car -what have I done so far? - Diff rebuild - OS GIKEN 100% Locking mechanism - GAZ GOLD Suspension - Dunlop Direzza Tires - Lightweight Bootlid - Lightweight Foldable Seats - Swapped all the different mounts/bushings. - Carbon Fiber front fenders. Future plans: - Total loss of over 180kg from swapping different bits SO all over all, what do you think? Should I do this? Has anyone done this here who can help tell me the benefits and cons of doing a rebuild. Any suggestions, opinions are welcome.