OK, I have an SLK32 AMG with Robs DCAI and a EURO 65mm pulley/tune running TORCO at 105octane and a tune to match. I don't see any cost efficient mods left. Any real power from doing a complete exhaust, 25-30whp minimum? Rob claims 15 from his downpipes which are costly and then I could do a resonator delete with a Borla Sport muffler or if a better fit a Borla Turbo Pro XS. Thoughts from experience please